UNITED NATIONS (AP) — Secretary-General Ban Ki-moon said Thursday the crisis in Syria is getting worse and claiming more lives every day even though President Bashar Assad’s government insists it is withdrawing troops ahead of a U.N. deadline to end the violence.

The U.N. chief appealed to Assad “to show vision and leadership” and keep his pledge to pull troops and heavy weapons out of cities and towns by April 10, and he urged the opposition to be ready to stop all violence if the Syrian government meets the deadline.

“Cities, towns and villages have been turned into war zones. The sources of violence are proliferating,” Ban told the U.N. General Assembly. “The human rights of the Syrian people continue to be violated. … Humanitarian needs are growing dramatically.”

His comments came as activists reported that Syrian troops attacked the Damascus suburb of Douma, an assault they said shows that Assad is intensifying violence in the days before the April 10 deadline. His crackdown on the yearlong uprising has left at least 9,000 people dead, according to the U.N.

Earlier Thursday, a U.N. team arrived in Damascus to start technical preparations for the possible deployment of U.N. monitors for any cease-fire between Syrian troops and rebel forces.

Kofi Annan, the U.N.-Arab League envoy trying to end the conflict, said Syria has informed him of partial withdrawals from three locations — Idlib, Zabadani and Daraa — “but it is clear that more far-reaching action is urgently required.”

“We must silence the tanks, helicopters, mortars and guns, and stop all other forms of violence too: sexual abuse, torture, executions, abductions, destruction of homes, forced displacement, and other such abuses, including on children,” he said.