* Annan sets 6 a.m. April 12 deadline for conflict's end
* Security Council endorses Annan's deadlines for Syria
* Russia, China support U.N. council statement
* Syria hints at possible loophole in Annan plan
UNITED NATIONS, April 5 (Reuters) - Syria faced pressure from all sides at the United Nations on Thursday as U.N.-Arab League envoy Kofi Annan set a precise deadline for an end to the conflict with clear backing from Russia, China and the rest of the U.N. Security Council.
Speaking by video link from Geneva, Annan told the 193-nation U.N. General Assembly he was urging "the government and the opposition commanders to issue clear instructions so that the message reaches across the country, down to the fighter and soldier at the local level" at 6 a.m. (0400 GMT) on April 12.
"We must silence the tanks, helicopters, mortars, guns and stop all other forms of violence too - sexual abuse, torture, executions, abductions, destruction of homes, forced displacement and other abuses, including on children," he said.
Syrian U.N. Ambassador Bashar Ja'afari, however, hinted at a possible loophole in Annan's peace plan, which does not refer to the withdrawal of police forces. He told reporters the police were not covered by the April 10 deadline because "the deployment of the police is to protect the civilians."
Opposition activists say the army and police have been responsible for killing civilians in the government's yearlong attempt to stamp out pro-democracy demonstrations.
The former U.N. chief spoke after the 15-nation Security Council unanimously adopted a "presidential statement" endorsing next week's deadline and warning Damascus of "further steps" if it did not meet the deadline, which the Syrians have accepted.
Annan's precise deadline and the latest council statement on the conflict backed by China and Russia, Syria's staunch ally and arms supplier, were the most recent examples of how U.N. pressure on Damascus to halt its yearlong assault is steadily increasing.
Russia and China twice vetoed resolutions condemning Syria, but in a diplomatic setback for Syrian President Bashar al-Assad have recently supported several statements urging Damascus to accept Annan's plan and allow humanitarian aid workers access.
It said the council "calls upon the Syrian government to implement urgently and visibly its commitments ... to a) cease troop movements toward population centers, b) cease all use of heavy weapons in such centers, and c) begin pullback of military concentrations in and around population centers."
The statement urges Damascus to "fulfill these in their entirety by no later than 10 April, 2012."
An earlier draft, obtained by Reuters, said the council "demands" compliance from Damascus. Western diplomats said the text was watered down to secure Russian and Chinese approval.
The agreed statement includes a second deadline that affects the opposition as well: "The Security Council calls upon all parties, including the opposition, to cease armed violence in all its forms within 48 hours of the implementation in their entirety by the Syrian government of measures a, b, c."
Annan made clear the second deadline for silencing all guns in accordance with his six-point peace plan will take effect at 6 a.m. Syrian time on April 12. In addition to a truce, Annan's plan calls for dialogue between the government and opposition on a "political transition" for the country.
Ja'afari blasted the president of the General Assembly, Qatar's U.N. Ambassador Nassir Abdulaziz al-Nasser, for holding Thursday's meeting on the Syrian conflict. Ja'afari said he was using the assembly to push the agenda of Qatar, which supports arming Syria's rebels.
"The PGA (president of the General Assembly) has misused his post ... to impose on member states the Qatari and Saudi agendas," he said, referring to the "so-called Syrian crisis."
"The PGA is a biased person, deceiving all of us, cheating on his mandate ... serving his national agenda," Ja'afari said.
U.N. Secretary-General Ban Ki-moon told the General Assembly that the violence in Syria was getting worse, despite Damascus' official acceptance of Annan's plan.
The Security Council statement asked Annan to update it on compliance with the timeline and warned that it "will consider further steps as appropriate." Russia and China, however, have made clear they would oppose any attempts to sanction Syria.
The United Nations says Assad's forces have killed more than 9,000 people in the past year in his attempts to crush pro-democracy demonstrations across the country. Syria told the world body last week that 6,044 had died, including 2,566 soldiers and police.
Western diplomats have expressed skepticism about Assad's intentions, noting he has broken previous promises to halt military action against civilian protesters.
The council also asks Ban Ki-moon to present proposals for a U.N. observer mission to monitor compliance with any future truce. As part of Annan's peace plan, the U.N. peacekeeping department is planning for a ceasefire monitoring mission that would have 200 to 250 unarmed observers. It would require a Security Council resolution.