Syrian rebels launched a series of attacks in Damascus on Tuesday, further undermining the shaky two-week-old UN-backed ceasefire.
The Britain-based Syrian Observatory for Human Rights said an intelligence official had been killed in the Barzeh neighborhood and state media reported that "a retired colonel and his brother" were killed in a different attack.
Three people were hurt when an army lorry was blown up as it drove through Damascus. Police said they did not believe the driver was involved and that explosives were planted on the vehicle.
UN monitors were said to be visiting the capital's Douma suburb on Tuesday but opposition activist Mohammed Saeed said he had no information about the visit and reported "tanks and shelling and gunfire" in the area.
"The army has prevented fire engines from entering the city," he claimed.
The 11-strong team of monitors is supposedly observing the ceasefire and preparing for a larger team to arrive, but the Syrian government cites ongoing attacks on military convoys and army checkpoints as reasons for not withdrawing its troops from all urban areas as demanded by UN envoy Kofi Annan's peace plan.
Opposition fighters say the government keeps attacking civilians and accused it of retaliating against people who greeted the team with anti-government protests.
A day after the monitors' visit to Hama on Sunday, over 30 people were allegedly killed by security forces.
Videos posted online by the opposition show corpses covered in white cloths, though the exact details can't be verified.
The UN says that over 9,000 people have been killed since the uprising began 13 months ago.
The World Food Programme said on Tuesday it would deliver food aid to 500,000 people in Syria "in the coming weeks."
The figure is a tenfold increase in aid since December but the agency warned that it would still leave a million Syrians without enough food.
With help from the Syrian Arab Red Crescent, the UN body began feeding Syrian refugees in Jordan this week and plans to get food to Homs, Hama, Idlib and Damascus soon.
Photo: In this photo released by the Syrian official news agency SANA, a UN observer, left, speaks with Syrian citizens during their visit to the pro-Syrian regime neighborhoods, in Homs province, central Syria, on April 23. United Nations observers monitoring Syria's shaky cease-fire visited a string of Damascus suburbs Monday, while the European Union looked set to levy new sanctions to increase the pressure on President Bashar Assad's regime. SANA/AP