BEIRUT - UN observers were on their way to the central Syrian village of Tremseh on Saturday, two days after activists said some 220 people had been killed there by helicopter gunships and militiamen, prompting international outrage. The United States has branded Syria's leaders murderers after the attack by Syrian President Bashar al-Assad's troops, but there was no break in the deadlock among world powers over how to bring about an end to the bloodshed. "We have sent a large integrated patrol today to seek verification of the facts," U.N. spokeswoman in Damascus Sausan Ghosheh said in an email. She said the patrol consisted of both civilian and military experts. UN Secretary-General Ban Ki-moon condemned what a U.N. reconnaissance mission on Friday said was "indiscriminate" bombardment on the central Hama province town, including rocket-firing helicopters. He questioned Assad's commitment to a UN-sponsored peace plan for Syria. Syria said the attack was a successful military operation that killed a large number of "terrorists" but no civilians. On Saturday morning, the British-based Syrian Observatory for Human Rights said 30 people had been killed across the country, several of them by an army bombardment in Homs province, a focus of the 17-month pro-democracy revolt that Western powers say has left 17,000 dead. In contrast to the United States, China said it strongly condemned "behavior which harms innocent civilians" but did not say who it believed carried out Thursday's attack on the town of Tremseh in rebellious Hama province. China and Russia continue to block Western efforts to impose harsher sanctions on Syria or take any steps Moscow and Beijing view as supporting "regime change" in Damascus. "We again urge all relevant sides in Syria to take practical steps, immediately stop all violence, (and) earnestly protect civilians," Chinese Foreign Ministry spokesman Liu Weimin said in a short statement. Accounts from opposition activists cited a death toll in Tremseh ranging from over 100 to more than twice that - either way one of the bloodiest incidents in 17 months of conflict. "We were surrounded from four sides ... with tanks and armored vehicles, and the helicopters were hovering above," said an unidentified man on amateur video footage purportedly filmed in Tremseh and posted on the Internet on Saturday.