NAJAF, Iraq – A Shiite insurgency appeared to be weakening last night as Iraqi forces moved to within 200 yards of the revered Imam Ali Shrine and Iraq’s defense minister once again demanded fighters loyal to a radical cleric surrender or face a violent raid.

The insurgent force, which once waged fierce battles with American troops throughout the Old City and Najaf’s vast cemetery, seemed considerably diminished in number and less aggressive after days of American air strikes and relentless artillery pounding.

In Baghdad, assailants bombed the convoys of two government ministers in separate attacks that killed five people and a suicide bomber, but left the ministers unharmed, officials said.

Hundreds of insurgents have been spotted leaving Najaf in recent days, witnesses said. Those that remained appeared to have pulled back to the area around the shrine, where the fighting yesterday was concentrated, American troops said.

American warplanes bombed the Old City late yesterday for the third night in a row, witnesses reported. Huge blasts rumbled throughout the city for about 10 minutes followed by gunbattles and smaller explosions.

Earlier in the day, fierce fighting broke out near the shrine compound, with rockets launched from American helicopters kicking up clouds of smoke and debris. Bradley fighting vehicles patrolling the nearly deserted, bullet scarred streets attacked insurgents, who responded with mortar fire and rocket-propelled grenades.

“We are under constant enemy small-arms, mortar, and RPG attack,” said American Lieutenant Chris Kent, whose unit was about 300 yards from the compound. “U.S. forces are consolidating positions to allow for future operations. Morale is very high.”

Iraqi forces, accompanying American troops into the Old City for the first time in recent days, combed through the neighborhood, approaching as close as 200 yards to the shrine, controlled by rebels loyal to radical cleric Muqtada al-Sadr.

The defense minister, Hazem Shaalan, addressing Iraqi National Guard troops in Najaf, said yesterday that Iraqi forces would head toward the shrine “tonight” to await the signal for a raid or the capitulation of the insurgents.

“When your brothers approach the holy shrine compound, they will direct calls of mercy to those [terrorists] to surrender,” Mr. Shaalan told the troops. “They have hours to surrender.”

By late yesterday, there was no indication Iraqi forces had advanced on the shrine.

Mr. Shaalan made a similar threat a week ago, saying the government could raid the shrine by the end of the day last Wednesday to free it of “its vile occupation.” The government later backed down and said it would work for a peaceful solution.

Any raid on the shrine, the holiest Shiite site in the country, risked igniting a massive Shiite rebellion throughout Iraq against the fledgling interim government, already battling a persistent and bloody Sunni insurgency.

“I tell Shaalan to throw his new declaration in the same garbage that he already threw his earlier declarations in,” al-Sadr aide Sheik Aws al-Khafaji told Al Jazeera television.

But other al-Sadr lieutenants reiterated their appeal for talks, a request the government has repeatedly rejected.

“We are ready to negotiate to end this crisis and the suffering of our persecuted people…but this government doesn’t want negotiations,” said Sheik Ali Smeisim, a senior al-Sadr aide.

The rebels have repeatedly accused American forces of damaging the shrine during the fighting. The American military accused the rebels of launching attacks from holy sites, but said it has restrained itself from attacking those positions.

The military released aerial photos yesterday purportedly showing a complete insurgent mortar system set up just outside the shrine compound.

Iraqi officials have said that any raid on the shrine would be conducted by Iraqi forces, since the presence of American troops at the holy site would future inflame Shiites here.

In other violence, clashes between British forces and Mr. al-Sadr’s rebels in the southern city of Amarah killed eight people and injured 18 others, said Dr. Saad Hemood, of the Zahrawi General Hospital.

The fighting started when insurgents attacked a British foot patrol with small arms and fired mortar rounds at a building housing British troops, residents said.