Top U.N. truce monitor in Syria, attack on Central Bank BEIRUT (Reuters) - A Norwegian general charged with overseeing a shaky U.N.-brokered truce in Syria arrived in Damascus on Sunday, boosting a monitor mission that activists say has helped ease the violence in the city of Homs, hotbed of a 13-month uprising. In the capital, militants fired rocket-propelled grenades at the Central Bank building, causing slight damage, and wounded four police when they attacked their patrol, state television reported. Activists in Damascus reported explosions and gunfire. "We will be only 300, but we can make a difference," Mood told reporters on his arrival in the Syrian capital. Damascus says 2,600 of its personnel have died at the hands of anti-Assad militiamen, and has accused the United Nations of turning a blind eye to "terrorist acts" against security forces. An activist in Homs, speaking via Skype, said violence had dropped sharply in the city since the observers deployed a permanent two-man team to the restive city last week. Despite the relative calm in Homs, the Syrian Observatory for Human Rights, a UK-based group tracking the conflict, said at last 39 people were killed across the country on Sunday, including civilians, security forces and rebels. Twenty-three civilians were killed, most of them shot by security forces in a single village in the central province of Hama, it said. Six rebel fighters were killed as well as seven members of the security forces - four of whom died when ammunition they were handling exploded. On Sunday an Islamist group called "al-Nusra Front" claimed responsibility for a suicide bombing that killed at least nine people in Damascus on Friday. "The problem is whether the Syrian government will agree to us deploying our own assets," he said late on Sunday. Ban said Syria's U.N. ambassador had promised unconditional cooperation. But it was difficult to "give full credibility on their promise, because they have not kept their promises," he told reporters during a visit to Myanmar. Additional reporting by Martin Petty in Naypyitaw, Myanmar; Writing by Ed Cropley; Editing by Louise Ireland and Stacey Joyce