Western powers pressed Syria to adhere to a ceasefire with only hours to go before the UN-backed deadline, as North Korea's plans for a rocket launch also raised mounting concern.
Foreign ministers of the Group of Eight major industrial nations met in Washington to plot the next steps in the global response as events unfolded rapidly in Syria and North Korea and ahead of talks on Iran's nuclear program.
Britain and France both said that they would press for international monitors in Syria if President Bashar al-Assad abides by a plan to end his bloody year-old crackdown by 6:00 am (0300 GMT) on Thursday.
French Foreign Minister Alain Juppe called for the UN Security Council to seek a "robust observers force" that would verify compliance and "could move freely" without interference from Assad's regime.
Britain backed the call for monitors and warned it would boost support for Syria's opposition and seek further sanctions if Assad does not comply with the ceasefire, part of a peace plan negotiated by former UN chief Kofi Annan.
"Our pressure on the regime -- its campaign of murder, torture and oppression -- must be intensified if Kofi Annan has not succeeded," Foreign Secretary William Hague told reporters after the first day of the two-day talks.
Separately, US President Barack Obama spoke by telephone with German Chancellor Angela Merkel and agreed on the need for "more resolute" action by the UN Security Council.
Obama and Merkel "shared the concern that the Assad government was not complying with the terms of the agreement negotiated by Kofi Annan and continued to engage in unacceptable brutality against its own people," a White House statement said.
The Syrian opposition also said there was no sign of compliance on the eve of the ceasefire deadline, reporting that 14 civilians were killed on Wednesday as regime forces kept pounding protest centers.
Western nations have demanded that Assad quit over the year-long crushing of the uprising. UN officials have said that more than 9,000 people have died since March 2011 and charged that Assad likely carried out crimes against humanity.
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Russia -- a member of the Group of Eight -- is the key military and diplomatic supporter of the Assad family, which has ruled Syria with an iron fist for four decades.
Russia has supported Annan's peace plan but said that the onus is on the opposition to halt the 13 months of violence.
Secretary of State Hillary Clinton hinted that she would seek to persuade Russian Foreign Minister Sergei Lavrov to use his influence to pressure Assad. Clinton said Tuesday she expected "a very rough couple of days" of diplomacy.
The Group of Eight -- Britain, Canada, France, Germany, Italy, Japan, Russia and the United States -- was also meeting as North Korea fueled a rocket to go ahead with a defiant launch of what the communist state calls a satellite.
Clinton said that the ministers "all share a strong interest in stability on the Korean peninsula" and would discuss "how best to achieve that."
"It violates multiple UN Security Council resolutions," Clinton told the ministers over lunch at the Blair House, the US residence for official guests across from the White House.
Pyongyang announced the launch plan as it marks the 100th anniversary of the birth of the regime's founder Kim Il-Sung, despite agreeing on February 29 to freeze its nuclear and missile programs in a deal with the United States.
As part of the package, the United States was to deliver badly needed food aid to the impoverished state, a plan that Washington has since suspended.
The Group of Eight also looked ahead to talks expected to open Saturday in Istanbul between six major powers and Iran, whose contested nuclear program has come under growing pressure from Israel and Western powers.
Clinton said that the talks offered "an opportunity for Iran to address seriously the international community's concerns."
"We believe there is still time for diplomacy, but it is urgent that the Iranians come to the table to establish an environment conducive to achieving concrete results through a sustained process," Clinton said.
Israeli and some Western officials accuse Iran of building a nuclear bomb, but the Islamic republic says its program is for peaceful purposes.