General George Casey (left) and Ambassador Zalmay Khalilzad (file photo)

The top U.S. officials in Iraq are urging Iraqis not to be drawn into an upsurge of sectarian violence.

In a statement Monday, General George Casey, the top U.S. commander in Iraq and Ambassador Zalmy Khalilzad condemned recent attacks in Baghdad. The statement urges Iraqis not to strike back and be used by those who seek to destroy the country.

In Washington, President Bush told a visiting Iraqi Shi'ite leader that the United States is not satisfied with the progress of efforts to stem the violence in Iraq.

Mr. Bush spoke after meeting at the White House with Abdel Aziz al-Hakim - leader of the Supreme Council of Islamic Revolution in Iraq, one of the largest factions in the Iraqi government.

Hakim said he opposes any regional or international effort that goes around the Iraqi government, stressing that Iraqis will solve Iraqi problems with the help of their friends.

In the latest violence in Iraq, gunmen killed an Iraqi radio journalist, Nabil Ibrahim al-Dulaimi outside his Baghdad home.

The U.S. military says four Marines died when a military helicopter made an emergency landing Sunday into water in western Iraq's Anbar province. Three Marines had been listed as missing, but their bodies have now been recovered.

A military statement says the incident does not appear to be a result of enemy action.

U.S. troops, meanwhile, have sealed off the northern town of Siniyah after insurgents carried out increasingly bold attacks. The U.S. military says it is letting in supplies of food and other necessities.

Some information for this report was provided by AP.