U.N. Secretary-General Ban Ki-moon says Syria's conflict is deepening and attacks by government forces on civilian areas show no sign of abating, despite assurances from Damascus that it has begun withdrawing troops ahead of a U.N. deadline to end the violence.

Mr. Ban Ki-moon told the General Assembly Thursday that the Syrian people had been “victims of horrendous abuse.” He said “cities, towns and villages had been turned into war zones.” He urged Syrian President Bashar al-Assad “to show leadership and vision” and keep his pledge to end violence by April 12.

In a speech via video link to the U.N. General Assembly Thursday, U.N.-Arab League envoy Kofi Annan said the Syrian government had accepted his six-point peace plan reached last month and urged Damascus to comply with the its provisions. He also admitted that progress in ending violence from the government crackdown on dissent is slow.

“We must silence the tanks, helicopters, mortars, guns and all other forms of violence too –sexual abuse, torture, executions, abductions, destruction of homes, forced displacements and other abuses, including on children.”

But Syria's ambassador to the U.N. Bashar Ja'afari said “the threat to the implementation of Mr. Annan's peace plan comes not from his government, but from countries like Saudi Arabia, Qatar and Turkey who he accused of financing and arming insurgents.”

Ja'afari said “Damascus wants written assurances from Mr. Annan that regional powers will not meddle in Syria's affairs or try to fill any political vacuum after April 12.”

Earlier Thursday, the U.N. Security Council adopted what is known as a “presidential statement,” calling on Syria to take urgent and concrete steps to stop the use of military power against its citizens.

The U.S. Ambassador to the U.N., Susan Rice, read the statement.

“The Security Council calls upon the Syrian government to implement urgently and visibly its commitments, as it agreed to do in its communication to the envoy of 1 April. To A: cease troop movement toward population centers, B: cease all use of heavy weapons in such centers, and C: begin pullback of military concentrations in and around population centers, and to fulfill these in their entirety by no later than 10 April 2012.”

Mr. Annan also confirmed that a small technical team has arrived in Damascus Thursday to begin laying the groundwork for a potential monitoring mission for peacekeepers. The team is led by Norwegian military chief Robert Mood.

He said that “what we need on the ground is a small, nimble U.N. team that could be deployed quickly with a broad and flexible mandate.”

Rights activists reported shelling and heavy gunfire Thursday in the Damascus suburb of Douma as well as in Idlib province and the central Homs region. The Syrian Observatory for Human Rights told VOA that 43 people were killed, most of them civilians.

The United Nations says more than 9,000 people have been killed in Syria since the uprising against Mr. Assad began 13 months ago.