DAMASCUS: Syria was under sharp international pressure Tuesday to halt its crackdown on pro-democracy protesters, as troops pursued a scorched earth campaign in northern mountains, sending thousands fleeing.

The United States stepped up its condemnation of the crackdown, which rights activists say has left at least 1,200 people dead since mid-March, and again called on its president to allow for a political transition or step aside.

“We have called on President Bashar Assad to cease the violence. We strongly condemn, in the strongest possible terms, the violence being perpetrated in Syria,” said White House spokesman Jay Carney. “President Assad needs to engage in political dialogue. A transition needs to take place. If President Assad does not lead that transition then he should step aside,” Carney told reporters aboard Air Force One.

Syrian troops using tanks and helicopters pushed toward a northern town on Tuesday after arresting hundreds of people in villages near Jisr Al-Shughour, residents said, as more refugees fled to Turkey.

More than 8,500 Syrians have sought shelter across the border to escape the latest military drive. Dozens of refugees with mud covering their boots and clothes clambered to a Turkish village to find bread for families waiting across the border in Syria in sodden makeshift camps.

“We are desperate here. We are under the rain, our children are sick. We have no medicine and no food,” said a crying woman with a baby lying next to her.

Meanwhile, Secretary of State Hillary Rodham Clinton accused Iran of supporting Syria in the brutal crackdown. Clinton said Tuesday in a statement issued in Washington that Iran’s complicity in abuses is coinciding with the two-year anniversary of its crackdown on citizens who protested after the contested election that handed another term to President Mahmoud Ahmadinejad.

Clinton said Iranians and Syrians yearn to be free.

Iran, meanwhile, accused Israel’s allies on Tuesday of interfering in Syria. “Some regimes, especially America and the Zionist regime, with particular aims, are provoking terrorist groups in Syria and in the region to carry out terrorist and sabotage operations,” Foreign Ministry spokesman Ramin Mehmanparast told a news conference.

Iran has voiced support for uprisings in most of the Arab world, but not Syria with which it has what it sees as a “line of resistance” against Israel.

Mehmanparast backed the Syrian government’s assertions that the three-month-old protests are part of a conspiracy backed by foreign powers.

Renowned Syrian poet and intellectual Adonis urged Assad to end his crackdown, in an open letter published on Tuesday.

“The Socialist Baath Party has not remained in power this long because of the strength of its ideology, but because of the power of its iron fist,” wrote the France-based Adonis, winner of this year’s prestigious Goethe Prize and one of the most popular poets and essayists in the Arab world.

“Experience shows that this fist ... can impose hegemony for a limited time only,” read the letter to Assad, published by Lebanon’s Arabic-language daily As-Safir. “It seems your destiny is to sacrifice yourself for your mistakes and to give back voice to the people and let them decide,” he wrote. Born in the Syrian mountain town of Qassabin, Adonis — like Assad — is a Alawite.