The international community on Friday continued to condemn Thursday's twin suicide bombings in southeast Iran, which has killed at least 28 people according to the latest tally.

Meanwhile, the Washington Post said there was an attempt in Iran to hold the United States at least partly responsible for the attacks, citing an Iranian state radio program saying the attacks were in line with US policies against Iran.

But the United States said earlier it condemns all forms of terrorism and sectarian-driven violence.

Jundallah, a mainly Sunni rebel group, has claimed responsibility for the attacks, saying that they were in retaliation against the government's execution of the group's leader Abdolmalek Rigi last month.

The majority of the Iranian population are Shiite.

Health Minister Marzieh Vahid Dastagerdi said Friday some 270 people were also injured in the attacks in front of a mosque in Zahedan, capital of Sistan-Baluchestan province, including some in serious condition.

Deputy Interior Minister Ali Abdollahi said a number of Revolutionary Guards were among the casaulties.

Iran has announced three days of public mourning in Sistan-Baluchestan and said the bodies of those killed would be buried on Saturday.

The UN Security Council Friday condemned the bombings "in the strongest possible terms."

"The members of the Security Council underline the need to bring perpetrators, organizers, financiers and sponsors of this reprehensible act of terrorism to justice," the council said in a statement.

"The members of the Security Council reiterate their determination to combat all forms of terrorism, in accordance with their responsibilities under the Charter of the United Nations," it said.

UN Secretary-General Ban Ki-moon also condemned the bombings in an earlier statement issued by his spokesman.

"This senseless act of terrorism at a place of worship makes it all the more reprehensible," the statement said.

Venezuelan President Hugo Chavez also voiced condemnation.

"The Venezuelan government and people express their deepest sympathy to the relatives of the victims of this coward crime, carried out with irrational hate against a group of innocent people," said a statement issued by the Venezuelan Foreign Ministry.

Media reports said the second bomb was detonated when people rushed to the scene about 20 minutes after the first blast, obviously in an attempt to maximize the casualties.

Abdolmalek Rigi, leader of the Jundallah group, was executed last month after being convicted of charges including armed robbery, bombings in public places, among others.

Iranian officials have said the group has links to the United States.

The Washington Post said in a Saturday report that Iran has "an apparent attempt to hold the United States at least partly responsible."

"America aims to support those grouplets who are able to carry out terrorist operations in Iran," Iranian state radio was quoted as saying.

Iran has long accused Washington of supporting separatist groups active in the country's western and eastern border areas.

Soon after the attacks, US Secretary of State Hillary Clinton issued a statement on Thursday, saying that "the United States condemns all forms of terrorism and sectarian-driven violence, wherever it occurs."