Egyptian President Mohammed Morsi offered nothing concrete to defuse the country's worst political crisis in nearly two years in a nationally televised speech late Thursday, refusing to rescind a disputed constitution drafted by his allies or his decrees giving him near absolute powers.

A night after thousands of his supporters and opponents fought pitched battles outside his Cairo palace that left at least six dead and nearly 700 injured, he angrily accused some of the opposition protesters of serving remnants of the old regime. He vowed never to tolerate anyone working for the overthrow of his "legitimate" government.

Some among the thousands of opposition protesters gathered near his palace raised their shoes in contempt as they listened to him. Others broke into the iconic Arab Spring chant of "the people want to topple the regime."

He also invited the opposition to a "comprehensive and productive" dialogue starting Saturday at his presidential palace, but offered no sign at all that he might offer any meaningful concessions.

The opposition has already stated that it would not enter a dialogue with Morsi unless he first rescinds decrees giving him nearly unrestricted powers and shelves the constitution draft hurriedly adopted by his Islamist allies.

He said the referendum on the disputed charter, at the heart of the crisis, will go ahead as scheduled on Dec. 15 despite opposition demands to shelve the document.

He also refused to rescind his decrees of Nov. 22 placing him above oversight of any kind, including by the courts, saying only that he was willing to annul one decree that gives him wide ranging powers to "protect" the nation and its revolution. He did not say how he would do that or give any other details.

Morsi, elected in June, was reading from prepared notes but frequently broke off to improvise.

The Egyptian president spent Thursday meeting with members of his cabinet and military leaders to discuss the expanding crisis after fierce street battles in an upscale residential suburb of Cairo killed five people and left more than 700 injured in the worst outbreak of violence between the two sides since the Islamist leader's election.

A journalist for the independent daily Al-Fagr newspaper was in critical condition Thursday after being shot in the head with a rubber bullet, according to a staff member who spoke to The Associated Press on condition of anonymity in exchange for releasing the information ahead of a formal announcement. The newspaper said it did not know who fired the rubber bullet.

Protesters defied an afternoon deadline to vacate the area, pressing forward with demands that Islamist leader Mohammed Morsi rescind decrees giving himself near-absolute power and withdraw a disputed draft constitution.

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An Egyptian army soldier stands guard next to a tank behind barbed wire securing the perimeter of the presidential palace while protesters, unseen on the other side, chant slogans against President Mohammed Morsi slogans on Thursday. (Nasser Nasser/Associated Press)

The intensity of the overnight violence, with Morsi's Islamist backers and largely secular protesters lobbing firebombs and rocks at each other, raised the specter that the two-week-old crisis that has left the country sharply divided would grow more polarized and violent.

Egypt has seen sporadic clashes throughout nearly two years of political turmoil after Hosni Mubarak's ouster in February 2011. But Wednesday's street battles were the worst between Morsi's supporters and opponents.

The clashes began after an implicit call by the Muslim Brotherhood and its political party, to which the president belongs, for their members to go to the palace and stage a sit-in that would remove anti-Morsi protesters who were camped out there.

Unlike Mubarak, Morsi was elected in June after a narrow victory in Egypt's first free presidential elections, but many activists who supported him have jumped to the opposition after he issued decrees on Nov. 22 that put him above oversight and a draft charter was later rushed through by his Islamist allies despite a walkout by Christian and liberal factions.

Compounding Morsi's woes, four of his advisers resigned Wednesday, joining two other members of his 17-member advisory panel who have abandoned him since the crisis began.

Six tanks and two armored vehicles belonging to the Republican Guard, an elite unit tasked with protecting the president and his palaces, were stationed Thursday morning at roads leading to the palace in the upscale Cairo district of Heliopolis. The guard's commander, Maj. Gen. Mohammed Zaki, sought to assure Egyptians that his forces were not taking sides.

"There will not be a tool to crush protesters and no force will be used against Egyptians," he said in comments carried by the official MENA news agency.

'I don't want Morsi to back down'

The situation was calm Thursday morning. Thousands of Morsi supporters had camped outside the palace after driving away opposition activists who had been staging a sit-in there, prompting fierce street battles that spread to upscale residential areas. The Brotherhood, which had erected metal barricades and manned checkpoints with rocks and empty glass bottles on hand overnight, withdrew from the area by Thursday afternoon.

"I don't want Morsi to back down," said Khaled Omar, a Brotherhood supporter who had camped out. "We are not defending him. We are defending Islam, which is what people want."

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Members of the Muslim Brotherhood and supporters of Egyptian President Mohammed Morsi gather around a fire outside of the Egyptian presidential palace early on Thursday. (Mahmoud Khaled/Agence France-Presse/Getty Images)

Other Brotherhood supporters outside the palace accused opposition protesters of being Mubarak loyalists or foot soldiers in a coup attempt.

"They want to take over power in a coup. They are conspiring against Morsi and we want him to crack down on them," said one, Ezzedin Khoudir. "There must be arrests."

Mohamed ElBaradei, a leading opposition reform advocate, said late Wednesday that Morsi's rule was "no different" than Mubarak's.

"In fact, it is perhaps even worse," the Nobel Peace Prize laureate told a news conference after he accused the president's supporters of a "vicious and deliberate" attack on peaceful demonstrators outside the palace.

Wednesday's violence also spread to other cities, with at least two Brotherhood offices set ablaze outside Cairo.