BERLIN — German Chancellor Angela Merkel has criticized Damascus allies China and Russia for blocking a Western-backed UN text demanding that inspectors probing chemical weapons use in Syria be given unfettered access.

Her comments were made in an interview with Focus magazine, extracts of which were published on Saturday, even as a top UN envoy arrived in Damascus to discuss the terms on an inquiry into the alleged chemical attacks.

"Unfortunately, the opposition of Russia and China thwarted a formal statement by the UN Security Council calling for them (the inspectors) to be granted full access," Merkel said.

A draft supported by the United States, Britain and France and calling for the powers of UN inspectors to be reinforced was circulated at a council meeting on Wednesday, in the wake of fresh allegations that chemical weapons had been used in Syria.

But according to diplomats, the council's two other permanent members China and Russia, blocked it and only agreed to a weaker statement.

"What matters now is that the UN inspectors who are already in Syria be allowed to reach the scene as soon as possible," Merkel said.

UN Under-secretary General Angela Kane arrived Saturday after the world body urged Syrian President Bashar al-Assad's regime and its opponents to cooperate with an investigation into the attacks said to have killed hundreds of people.

Opponent to Assad said the president's forces killed 1,300 people when they unleashed chemical weapons east and southwest of Damascus in the attacks on Wednesday.

The Syrian government has strongly denied the accusations, but so far it has not said whether it will let UN inspectors visit the sites.