UNITED NATIONS - UN Secretary-General Ban Ki-moon said Thursday the UN fact-finding team is "on stand-by and ready to deploy in 24-48 hours" to investigate the alleged use of chemical weapons in attacks in Syria.

"The fact-finding team is on stand-by and ready to deploy in 24-48 hours," UN spokesman Martin Nesirky told reporters here late Thursday. "The secretary-general has consistently urged the Syrian authorities to provide full and unfettered access to the team. He renews this urgent call today."

A member of the Free Syrian Army holds his weapon as he sits on a sofa in the middle of a street in Deir al-Zor, in this April 2, 2013 file photo. [Photo/Agencies]

On April 8, the Syrian Foreign Ministry said that the UN request to conduct a full investigation about chemical weapons on all Syrian territories runs counter to the request of the Syrian government.

The Syrian government has recently asked the United Nations to send a technical team to the northern town of Khan al-Asal to investigate what the government said was a chemical attack by the rebels, which killed more than 50 people and left scores of others at hospitals, stressing that the technical team should conduct its work only at the targeted site.

However, the opposition groups in exile called on the United Nations not only to send a technical team but also to conduct a full investigation.

The UN spokesman made the statement in response to a press question hours after the White House said that the Syrian government has probably used chemical weapons on a small scale in the Middle East country's armed conflicts, but insisted that US President Barack Obama needed definitive proof before he would take action.

"The secretary-general has taken note of the letter from the White House to Congress regarding chemical weapons in Syria," Nesirky said. "He takes seriously the assessment presented in that letter."

"However, the United Nations is not in a position to comment on assessments based on national intelligence information," said the UN spokesman. "Senior advisers at UN Headquarters have been in contact with the US authorities on the latest developments."

"The secretary-general has already put together a technical expert team to conduct a fact-finding mission to look into all serious allegations of the possible use of chemical weapons in Syria," he said. "He has requested supporting information from the relevant Member States."

On March 26, Ban announced the appointment of Professor Ake Sellstrom of Sweden to head the UN fact-finding mission, which is tasked to investigate alleged use of chemical weapons in Syria.

Ban and other top UN officials already made it clear that the UN technical team, if allowed into Syria, will only conduct an investigation to find out whether the chemical weapons had been used in the Syrian violence, but will not give any opinion on who used them.

On Tuesday, Israel's top military analyst, Brig. Gen. Itai Brun, told a security conference in Tel Aviv that the Syrian government had used chemical weapons, reports said.

Last month, Britain and France voiced similar concerns to the United Nations. In letters to Ban, France and Britain laid out allegations of chemical weapons attacks in the Syrian city of Aleppo and suburbs of Damascus on March 19, urging a thorough investigation from the world body.