Iranian opposition group the National Council of Resistance said Thursday it has agreed to begin evacuating its long-time base in a camp in central Iraq to transfer to a UN-approved site near Baghdad.

According to a statement issued by the exiled group's base in Paris, NCRI leader Maryam Rajavi has agreed that the first 400 of 3,400 refugees based in Ashraf camp will be transferred to Camp Liberty, a former US military base.

The statement said Rajavi had received assurances from US Secretary of State Hillary Clinton before agreeing to order the move.

"This is despite the fact that there was no agreement on the transfer of all their vehicles and personal movable property to Liberty," the statement said, while calling for better guarantees for the residents' safety.

The NCRI, which includes the People's Mujahedeen of Iran, demanded Iraqi police be removed from the Liberty site before any more of the group leave Ashraf, which Baghdad has vowed to close.

Thursday's statement said that this demand was necessary "to avoid tension, violence and another massacre of the residents. This is particularly important for the security and peace of female residents."

In Washington, US State Department spokeswoman Victoria Nuland said: "The United States urges this voluntary movement to Hurriya (Liberty in Arabic) to begin on schedule February 17.

"The US will not walk away from the people at Camp Hurriya," she said in a statement.

"We will visit Hurriya regularly and frequently, and continue to work with the UN to support their temporary relocation and subsequent peaceful and secure resettlement outside of Iraq," Nuland said.

The NCRI has been in revolt against Tehran's Islamic regime for more than three decades. While many of its members are living in exile around the world, its biggest base is in Ashraf in Iraq, near the Iranian border.

From there, the People's Mujahedeen fought alongside Saddam Hussein's Iraqi forces against their Iranian countrymen during the Iran-Iraq war.

The camp came under US forces' control after their 2003 invasion toppled Saddam, and they oversaw the safety of its inhabitants until January 2009, when they transferred security for the camp to Iraq.

Under pressure from Tehran, the post-Saddam Iraqi regime now wants to close the camp and expel its inhabitants, but they have thus far refused to budge, seeking security guarantees and a new life abroad.

Ashraf residents are being assessed individually by the office of the UN High Commissioner for Refugees after applying for refugee status, to allow them to resettle elsewhere, but Baghdad is becoming impatient.

Under a pact signed on December 25 between the United Nations and the Iraqi government, the residents of camp Ashraf will be transferred to Camp Liberty, a former US military site near Baghdad's international airport.

The NCRI is in negotiations with the United Nations over the transfer, but has repeatedly complained that living conditions at Liberty are not adequate.

"Camp Liberty does not fulfill international humanitarian and human rights standards such as freedom of movement, which was raised by (UN refugee agency) the UNHCR, and there is no free access to medical services, lawyers and families," it said.