A senior Israeli official said Wednesday that it is "apparently clear" that chemical weapons were recently used in Syria, and that the alleged attack will be a main topic of conversation with visiting President Barack Obama.

The statement by Yuval Steinitz, the newly appointed minister of intelligence and strategic affairs, conflicts with U.S. assessments that there is no evidence behind accusations traded the day before between Syrian rebels and the Bashar Assad government of a chemical weapons attack in a village in the north of the country.

Steinitz, who was speaking to Army Radio, did not say how he came to the conclusion that the weapons were used. He would not comment on whether it was Assad forces or the rebels that used them, saying it was not important.

A senior defence official told the Associated Press that he concurred chemical weapons had been used, basing that on intelligence reports. He would not elaborate.

Israel has repeatedly expressed concern that Syria's chemical arsenal could fall into the hands of anti-Israel militants like Lebanon's Hezbollah, an Assad ally, or an al-Qaeda-linked group fighting with the rebels.

Steinitz said that after Iran's nuclear program, the fate of Syria's chemical weapons is the second most urgent issue that will be discussed with Obama during his 48 hour visit that begins Wednesday afternoon.

"It is apparently clear that chemical weapons were used," Steinitz said. "The fact they apparently used chemical weapons against civilians needs to worry us and shows the urgency of taking care of the issue," he said.

31 killed in village attack

Syrian rebels and Assad's government blamed each other Tuesday for a chemical attack on a northern village. There have been many reports and rumours of such weapons being used throughout the war but no attack has yet been confirmed. The U.S. said there was no evidence chemical weapons were used.

President Barack Obama has declared the use, deployment or transfer of the weapons would be a "red line" for possible military intervention by the U.S. in the Syrian conflict.

The Syrian state-run SANA news agency said "a missile containing a chemical substance" was fired at the village of Khan al-Assal in Aleppo province by "terrorists" — the term it uses for rebels. Syria's Deputy Foreign Minister Faysal Mekdad said 31 people were killed.

SANA added that more than 100 others were wounded, some of them critically, and it published pictures showing casualties, including children, on stretchers in what appears to be a hospital ward. None showed signs of physical injuries. The rebels quickly denied using chemical weapons and accused government forces of doing so.

On Wednesday, the Syrian government asked UN Secretary-General Ban Ki-moon to appoint an independent mission to investigate the alleged weapons attack.

Syria's UN Ambassador Bashar Ja'afari stressed to reporters that Syria is a party to most UN conventions on chemical, biological and nuclear weapons and had proposed a Security Council resolution in 2003 when it was a council member that would have required the Middle East to be free of all weapons of mass destruction. He said it was blocked by the threatened veto of an "influential member," an apparent reference to the U.S., Israel's closest ally.

The Aleppo Media Center, however, affiliated with the rebels, said there were cases of "suffocation and poison" among civilians in Khan al-Assal after a missile was fired at the area. It said in a statement the cases were "most likely" caused by government forces' use of "poisonous gases."

Israel says it is trying to stay out of Syria's civil war, although it has strongly signalled that it was responsible for an airstrike in January and suggested it was targeting a Hezbollah convoy carrying anti-aircraft missiles to Lebanon. It is concerned however about violence spilling into northern Israel.

Jordan warns of extremist elements in Syria

Meanwhile, Jordan's king warned Wednesday that a jihadist state could emerge on his northern border in Syria with extremists trying to establish a foothold in the neighbouring country.

Syrian President Bashar Assad was beyond rehabilitation, King Abdullah II said, and it was only a matter of time before his authoritarian government collapses.

"The most worrying factors in the Syrian conflict are the issues of chemical weapons, the steady flow or sudden surge in refugees and a jihadist state emerging out of the conflict," the king said.

"Another extremely dangerous scenario is the fragmentation of Syria, which would trigger sectarian conflicts across the region for generations to come," he said. "And also the huge risk that Syria could become a regional base for extremist and terrorist groups, which we are already see establishing firm footholds in some areas. All these are extremely dangerous threats," he said.