Updated

China said Thursday that it was considering sending observers to monitor a truce in Syria, where there are fears that a U.N.-brokered cease-fire may unravel.

The United Nations has been working to strengthen a cease-fire plan developed by special international envoy Kofi Annan that includes monitors, although the final number and makeup of the monitors have not been set.

Since a truce formally took effect last week, Syria has violated key provisions. Tanks, troops and widely feared plainclothes security agents continue to patrol the streets to deter anti-regime protests.

Foreign Ministry spokesman Liu Weimin told a regular news conference that Beijing was "seriously considering the issue of sending people to join the U.N. observers." He did not give details.

U.N. Secretary-General Ban Ki-moon says he believes there is an opportunity for progress in Syria and recommended the Security Council approve a 300-strong U.N. observer mission.

In a letter obtained by The Associated Press, Ban told the council he would consider developments on the ground, including consolidation of the cease-fire, before deciding on when to deploy the expanded mission, which is larger than the 250 observers initially envisioned.

Liu said it would be up to an advance team of U.N. observers in Syria to decide on the number.

The week-old cease-fire was supposed to allow greater humanitarian and other relief to enter the country, but further violence was reported Thursday morning.

The Britain-based Syrian Observatory for Human Rights said clashes between troops and army defectors in the eastern city of Deir el-Zour had left at least one person dead and wounded three civilians.

Activists said Syrian troops also shelled rebel-held neighborhoods in the central city of Homs and the nearby town of Qusair, which borders Lebanon.

The Observatory said intense shooting and explosions could be heard in Homs' Qarabees and Jouret el-Shayah neighborhoods.