The UN-Arab League envoy for Syria says countries with influence should to step up the pressure on Syria and rebel groups to end violence in the country.
Speaking in Geneva, Kofi Annan said time was running out to implement his six-point plan for Syria, and he had invited world powers to meet in Geneva to discuss it on June 30.
Annan told reporters that it was still uncertain whether the meeting would go ahead.
He also said Iran should be part of a solution to the crisis.
Meanwhile, reports say about 25 people have been killed in a village in the latest bloodshed in Syria, according to reports.
Syrian opposition sources and state-run television both said around 25 people had been killed in the Darat Azzah village in the northern Aleppo Province.
The pro-opposition Syrian Observatory for Human Rights on June 22 distributed a video that claimed to show 26 dead bodies.
The group described those killed as members of the pro-government Shabiha militia.
In its report, state-run television said 25 people had been killed by "armed terrorists" in Darat Azzah.
Syria Olympic Chief Refused U.K. Visa
In other news, Britain has refused to issue a visa for Syrian National Olympic Committee chief Mowaffak Joumaa to travel to London for next month's Olympic Games.
Britain's "The Guardian" newspaper reported Joumaa had submitted his visa request last week and was subsequently turned down.
Joumaa, who is not among the Syrian officials included on the European Union travel-ban list, is a close associate of Syrian President Bashar al-Assad.
British media reported his relationship to Assad was a factor in denying Joumaa a visa.
Criticism over Syrian authorities' crackdown on opposition groups led Britain and other countries to expel Syrian diplomats.
British Prime Minister David Cameron has already said that Syrian athletes would be welcome at the London games.
Based on reporting by Reuters, AFP, AP, and dpa