Baghdad, Iraq ? Five Iranians detained by U.S.-led forces were working in a decade-old government liaison office that was in the process of being upgraded to a consulate, the Iraqi foreign minister said Friday.

But Deputy U.S. State Department spokesman Tom Casey said in Washington that the U.S.-led forces entered the building because information linked it to Iranian elements engaging in violent activities in Iraq.

Tehran condemned the raid in the Kurdish-controlled northern city of Irbil and urged Iraq to push for the Iranians’ release.

Iraqi Foreign Minister Hoshyar Zebari said the building where the Iranians were detained Thursday had operated with Iraqi government approval for 10 years.

“We are now in the process of changing these offices to consulates,” he said. “It is not a new office. This liaison office has been there for a long time.”

The diplomatic tussle came at an unwelcome time for the U.S. as President Bush faces criticism over his new strategy for ending the violence in Iraq. Bush also vowed to isolate Iran and Syria, which the U.S. has accused of fueling attacks in Iraq.

Iraqi President Jalal Talabani plans a trip to Syria on Sunday, the highest-level Iraqi visit to the country in more than 24 years. The neighbors restored diplomatic relations in December that were cut in 1982 amid ideological disputes between Damascus and the regime of Saddam Hussein.

Radical Shiite cleric Muqtada al-Sadr’s office, meanwhile, rejected Bush’s plan to send 21,500 more troops to Iraq as part of an effort to curb sectarian attacks.

“We reject Bush’s new strategy and we think it will fail,” said Abdul-Razzaq al-Nidawi, a senior official in al-Sadr’s office. He said Iraq’s problems were due to the presence of U.S. troops and called for their withdrawal.

Local leaders of al-Sadr’s Mahdi Army militia, which has been blamed for much of the sectarian violence, said they were bracing for an attack and avoiding appearing in public with their weapons.

Zebari’s Iranian counterpart, Manouchehr Mottaki, called on the Iraqi government to secure the release of the five Iranians, Iranian state television reported. “Such illegal and adventurous acts by the U.S. should be stopped,” the broadcast quoted Mottaki as saying.

Mottaki condemned the raid, saying it contravened the Vienna Convention. “This behavior by the United States contradicts its claims of providing security in Iraq,” he was quoted as saying.