U.N.-Arab League envoy Kofi Annan said a Syrian cease-fire should take effect on April 12 but he admitted that progress is slow in ending violence from the government crackdown on dissent.

In a speech via videolink to the U.N. General Assembly on Thursday, Mr. Annan urged the government to comply with provisions in a six-point peace plan that he brokered with Syria in March.

The U.N. Security Council called on Damascus to “implement urgently and visibly” its commitments, including compliance with an April 10 deadline to pull its forces out of urban areas.

A U.N. peacekeeping planning team arrived in Syria to begin laying the groundwork for a potential monitoring mission for peacekeepers. The team, led by Norwegian military chief Robert Mood, was in Damascus on Thursday.

Rights activists reported shelling and heavy gunfire Thursday in the Damascus suburb of Douma and additional fighting in northern Aleppo province near the Turkish border.

U.N. Secretary-General Ban Ki-moon told the General Assembly that the Syrian people had been “victims of horrendous abuse.” He said “cities, towns and villages had been turned into war zones.”

Mr. Annan said Syria had begun withdrawing troops from three areas of the country as part of the negotiated cease-fire plan.

Mr. Annan's spokesman, Ahmad Fawzi, told reporters in Geneva that in spite of continued violence in Syria, negotiators still expected Damascus would honor its committments.

“We have no doubts that we have this commitment. They have agreed to the six-point plan. They have agreed to the 10th of April deadline.”

Turkey's disaster management agency said Thursday more than 1,600 Syrians fled into Turkey in the past two days.

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

The International Committee of the Red Cross said Syria had agreed to allow the relief organization to expand its humanitarian mission in the country.

The Red Cross says the agreement includes a plan to “pause” fighting in affected areas so that it can begin a humanitarian mission. The agreement resulted from talks between Syrian officials and Red Cross chief Jakob Kellenberger.