Members of the Communist Party distribute sweets to Iraqi security forces to celebrate the withdrawal of U.S. troops in Baghdad on Tuesday. (Mohammed Ameen/Reuters)

Iraqi Prime Minister Nouri al-Maliki assured his people Tuesday that government forces taking control of urban areas are more than capable of protecting the country — even as a car bomb exploded in the northern city of Kirkuk, killing at least 24 people and wounding dozens.

"Those who think that Iraqis are not able to protect their country and that the withdrawal of foreign forces will create a security vacuum are committing a big mistake," al-Maliki said in Baghdad in a nationally televised address.

The Iraqi government named June 30 National Sovereignty Day, declaring it a public holiday. People celebrated the day with fireworks, and thousands attended a party in a park where singers performed patriotic songs.

In Washington, U.S. President Barack Obama said Tuesday there will be more work — and likely more violence — in the days ahead, but Iraq will prevail as a stable, sovereign nation.

"Iraq's future is in the hands of its own people," he told a news conference at the White House. "The Iraqi people are rightly treating this as a cause for celebration. The future belongs to those who build, not to those who destroy."

People stand by a fire at the site of a bomb attack in Kirkuk, Iraq on Tuesday. (REUTERS)

There had been a significant spike in violence before Tuesday's withdrawal, with more than 250 people killed in a series of bombings. Al-Maliki blamed the attacks on al-Qaeda in Iraq and the remnants of Saddam Hussein's Baath party.

Al-Maliki's remarks came a day after four U.S. soldiers were killed in combat as the American military completed a withdrawal from Iraq's cities.

The troop withdrawal was the first step in the U.S.-Iraqi security pact that will see all American forces withdraw from the country by Dec. 31, 2011.

The midnight handover to Iraqi forces made citizens proud, but many fear the 650,000-member Iraqi military is not ready and that violence will rise — Shias fear more bombings by Sunni Militants while Sunnis fear that the Shia-dominated Iraqi security forces will give them little protection.

The 130,000 U.S. troops who remain will continue combat operations in rural areas and near the border, and will return to the cities only if asked.

With files from The Associated Press