BAGHDAD, Iraq (AP) - Huge explosions rocked central Baghdad on Tuesday night, and Iraqi police said two mortars landed inside the compound used as a headquarters of the U.S. occupation.

Four large explosions could be heard about 7:45 p.m., and smoke could be seen rising from the northern end of the U.S. compound near the al-Jamhuriya Bridge over the Tigris River.

The U.S. military command confirmed two impacts in the city center but did not say where. Iraqi police said two of the rounds impacted in the U.S.-controlled "green zone," a one-square-mile area along the western bank of the Tigris where the coalition headquarters is located.

It was the second straight night of heavy explosions in the center of the Iraqi capital. About three mortars impacted on the city late Monday. U.S. authorities said at least one hit a U.S. Army base but caused no damage or casualties.

Foreign Minister Ana Palacio said the Spanish Embassy will remain open, however all but four of the 29-member staff would leave, most for Amman, Jordan. Spain has about 1,300 soldiers in Iraq and was one of the strongest supporters of the U.S.-led invasion,

"We have taken staff out of Baghdad temporarily given that it is a very complicated moment," Palacio said in Berlin. Spaniards working for the U.S.-led Coalition Provisional Authority will stay, the Spanish Defense Ministry said without giving their number.

Spain became the third coalition member to withdraw diplomats from Iraq due to stepped up insurgent attacks. Last month, Bulgaria and the Netherlands moved their diplomats to Jordan, also citing worsening security.

Those fears increased after a dramatic escalation in attacks, starting with the Oct. 26 missile barrage against the Al-Rasheed Hotel, where many coalition and U.S. military officials lived. One U.S. colonel was killed and 18 people were injured.

Violence continued Tuesday when a roadside bomb killed a 1st Armored Division soldier and injured two others in Baghdad.

In the northern city of Mosul, insurgents using small arms fire and rocket-propelled grenades Tuesday attacked a hotel housing American troops but caused no casualties, the military said.

Three of the grenades hit the building and two others landed in the compound as U.S. troops returned fire. A police station in Mosul was also struck overnight by a rocket-propelled grenade, the military said Tuesday. There were no casualties.

Also in Mosul, Iraq's third largest city which had been relatively quiet, gunmen Tuesday killed a judge near his home. Ismail Youssef, a Christian, was the second Iraqi judge assassinated in as many days.

Elsewhere, insurgents Tuesday ambushed a U.S. patrol with RPGs in the town of Khaldiyah, located west of Baghdad in the volatile "Sunni Triangle," witnesses said. There were no reports of casualties and no confirmation from the U.S. command.

The Arabic language satellite television station Al-Jazeera reported an ambush Tuesday near Samara north of the capital and broadcast pictures of cheering Iraqis displaying American ammunition as a truck burned in the background.

U.S. troops, meanwhile, raided the village of Karasia near Tikrit late Monday, arresting two suspects and seizing Kalashnikov rifles, 14 mortar rounds, a mortar tube, and rocket-propelled grenades and launchers, the military said.

In Mosul, gunmen killed a provincial judge Tuesday near his home. Ismail Youssef, a Christian, was a deputy to the head of the appeal courts in Nineveh province. On Monday, the head of an Iraqi court who was investigating members of Saddam Hussein's Baath Party, Muhan Jabr al-Shuweily, was abducted and murdered in the southern city Najaf.

The Spanish withdrawal followed the death of a Spanish navy captain in the truck bombing of the United Nations headquarters in Baghdad on Aug. 19, and the Oct. 9 killing of a Spanish sergeant working for that nation's military intelligence. Security at the Spanish embassy had been stepped up in recent weeks.

After months of attacks and ambushes on U.S. soldiers in Iraq, insurgents have begun targeting diplomatic and humanitarian facilities - mainly with vehicle bombs and suicide attackers.

The Oct. 14 explosion outside the Turkish Embassy killed a bystander. A day before the Dutch announced their diplomats were leaving, four suicide bombings hit the International Red Cross headquarters and four Iraqi police stations in Baghdad, killing 40 people, mostly Iraqis.

The Bush administration has urged other countries to send troops to Iraq to relieve the burden on American soldiers. Turkey agreed last month to send soldiers here but the move was stalled by widespread opposition, including from pro-U.S. Kurds in the north.

Turkey has fought a 15-year battle with independence-minded Kurdish militants and continues to station thousands of troops just inside Iraq's northern border.

Turkey's ambassador to the United States said Tuesday in Washington that his country will not send troops into Iraq without an invitation from the U.S.-appointed Iraqi Governing Council.

Ambassador Osman Faruk Logolu said the United States must put more pressure on the council to approve the Turkish troops - a move he said the United States appears unwilling to make.

"Until we have a clear initiative from the Iraqi people, we will not insist on going into Iraq," Logolu said at a breakfast meeting with reporters. "Ours is an offer to help ... We want to make sure that if we go to Iraq we will be welcomed."