A UN inspection team is in Cyprus and ready to deploy to nearby Syria to probe the alleged use of chemical weapons in the conflict there, UN Secretary General Ban Ki-moon said on Monday.

"I can announce today that an advance team is now in Cyprus, the final staging point" before the mission heads to Syria, Ban said in The Hague. "We are ready."

Ban said at the opening of the third review of the Chemical Weapons Convention at the Organisation for the Prohibition of Chemical Weapons (OPCW) that they still needed the Syrian regime's go-ahead.

"The UN is now in the position to deploy in Syria -- in less than 24 hours all logistical arrangements will in place," Ban said after President Bashar al-Assad called on the UN to probe allegations rebels had used chemical weapons.

"All we are waiting for is the go-ahead of the Syrian government to determine if any chemical weapons have been deployed," Ban said.

"We are still in the process of discussing it with the Syrian government."

Diplomats said last week that Syria had not yet agreed to give the "unfettered access" demanded by the United Nations for its chemical weapons probe, despite asking for the UN to investigate its accusation that rebels used chemical weapons in Aleppo province.

Britain and France have demanded that the enquiry also take up opposition claims that the government staged that attack and two other allegations that the government used chemical weapons.

"My position is clear -- all claims will be examined without delays, without conditions and without exception," Ban said, adding that a list of 15 chemical experts of the OPCW had been provided and that the bulk of the team would come from the OPCW.

Ban said that the advance team in Cyprus "is very small" and that time was of the essence.

"The longer it takes the harder it will be," to investigate the claims, he said.

OPCW head Ahmet Uzumcu said the security situation in war-wracked Syria would be an issue for the inspectors.

"The security issue on the ground is a matter of concern," Uzumcu said.

Ban last week named Swedish scientist Ake Sellstrom, a veteran of 1990s arms investigations in Iraq, to head the enquiry.

Ban has repeatedly demanded that the physics, chemical and health experts be given "unfettered access" in Syria to determine whether chemical weapons have been used in the two-year-old conflict.

Syria is not a member of the Chemical Weapons Convention and is believed to have a large stock of sarin and other nerve gases.

Ban does not want experts from the Security Council permanent members -- Britain, China, France, Russia and the United States -- on the team because of the political sensibilities, diplomats said.

No experts from Turkey or Arab countries are expected to take part for the same reasons. Most of the experts are expected to come from Latin American, European Nordic and Asian countries.

Syria asked for an investigation over two weeks ago into its allegation that the opposition used chemical weapons near the city of Aleppo on March 19.