WASHINGTON: United Nations, United States, Britain, Canada, Saudi Arabia, Lebanon, Turkey, Iran, Hamas party and Jordan have condemned Wednesday’s blast that heavily damaged one of the holiest sites of the Islamic World in Samarra, Iraq.

White House Press Secretary Scott McClellan called it a "brutal attack" -- and says it shows the terrorists behind the assault are "the enemies of all faiths and of all humanity."

"On behalf of the American people, the president extends our deepest condolences to the people of Iraq for this brutal attack on one of Iraq's holiest sites," McClellan said.

"The bombing was a brutal, anti-Islamic and inhuman act. Such terrorist acts run counter to religious and divine values and stirred up hatred among Muslims," Iran Foreign Ministry spokesman Hamid- Reza Asefi was quoted by the official IRNA news agency as saying.

Asefi said that Iran was confident that such acts could "not harm the strong will of Muslim Iraqi people and their national unity and solidarity and unity of Islamic nations as well."

Later, Iranian Supreme Leader Ali Khamenei announced one week of national mourning to mark the incident.

Meanwhile, Turkish Foreign Ministry said in a statement that the aim of those who were staging terrorist attacks was to launch a sectarian and ethnic conflict.

Addressing a joint press conference with US Secretary of State, Saudi Foreign Minister Prince Saud Al-Faisal said: with regard to terror act that happened in Iraq, we are against terrorismin general and against terror activities that target holy sites.

British Prime Minister Tony Blair condemned the bombing as an attempt to cause religious strife and derail democracy in the country.

In a statement released by his office, Blair said: "I condemn utterly today's attack on the Askari shrine in Samarra, one of the holiest religious shrines.

"The perpetrators of this attack had one motive and one alone -- they want to cause strife and violence between Sunni and Shia, to derail democracy currently taking hold in Iraq," Blair said.

"People must not fall into the trap being set for them. It is vital that all groups in Iraq show restraint in the face of this blatant provocation," he added.