President Bashar al-Assad's government had blocked the inspectors since calling for a UN inquiry into the use of the banned arms in March.

"The mission will travel to Syria as soon as possible to contemporaneously investigate three of the reported incidents," said UN spokesman Martin Nesirky.

The announcement followed an accord reached with the Syrian government when two UN envoys went to Damascus last week.

The inspectors, who are led by Swedish expert Ake Sellstrom, are being assembled in Europe and could go to Syria as soon as next week, diplomats said.

The announcement that inspectors will get into Syria is seen as a major breakthrough in one of the most frightening aspects of the 28-month-old war.

The United Nations says reports on 13 different chemical attacks have been made. Syria, Britain, France, Russia and the United States have all handed over evidence to Sellstrom's team.

Khan al-Assal, which is one of sites on the initial investigation list, is now the scene of major fighting between government troops and foreign backed terrorist groups.

While the initial inquiry will focus on three sites, Nesirky said UN leader Ban Ki-moon "remains mindful of other reported incidents and the mission will also continue to seek clarification from the member states concerned."

The spokesman said the first sites on the UN list includes Khan al-Assal, near Aleppo, where the government reported a chemical weapons attack on March 19. It said at least 26 people, including 16 soldiers, were killed.

Assad's government and Russia blame Syrian militants for the attacks.

The other two sites on the initial list are Ataybah near Damascus, where an alleged attack was staged in March, and Homs, where chemical weapons are alleged to have been used on December 23, diplomats said.

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