Syria on Tuesday accused Washington of encouraging more massacres in the strife-torn country and of meddling in its internal affairs.

"The U.S. administration is pushing forth with its flagrant interference in Syria's internal affairs and its backing of armed terrorist groups," the foreign ministry said in a statement.

The U.N. Security Council on Tuesday unanimously passed a resolution threatening sanctions against groups seen undermining Yemen's political transition and staging attacks in the country.

So-called "spoilers" such as the family and supporters of former president Ali Abdullah Saleh, though not named in the resolution, are a particular target of the warning in Resolution 2051, diplomats said.

Six far-right militants were arrested Tuesday after four Egyptians were assaulted in an industrial suburb of Athens, police said, amid an increase in attacks on immigrants in the crisis-hit nation.

A local Muslim leader accused Greek politicians, particularly those on the right, of stoking racist violence ahead of a general election on Sunday that could determine whether the country will stay in the eurozone.

Iran on Tuesday welcomed a Russian proposal on holding an international conference on Syria aimed at saving a faltering peace plan for that country's conflict.

"We support any method which helps positive talks between the government and the opposition in an appropriate environment, and also suitable reform actions for realizing the people's ambitions," Iranian foreign ministry spokesman Ramin Mehmanparast told reporters at a weekly press briefing.

Pro-Syrian regime villagers on Tuesday prevented United Nations observers from reaching the town of Al-Haffe where there are fears that a new massacre might be carried out, a watchdog said.

"Residents of the pro-regime village of As-Sheer blocked the road and prevented the U.N. observer team from reaching Al-Haffe," the Syrian Observatory for Human Rights said.

The Vatican's position "is unchanged" on the annexation of east Jerusalem, a Holy See negotiator said Tuesday, amid concern among Palestinian officials about possible concessions.

"The Holy See's position has not changed," negotiator Ettore Balestrero told the Vatican Radio after biannual talks between Israel and the Holy See on the status of Catholic Church property.

A Saudi trade body cancelled a Tuesday meeting with a Russian delegation of businessmen in protest at Moscow's position on the Syrian uprising, a top official said.

"The Chamber of Commerce and Industry in Riyadh has cancelled a scheduled meeting with a delegation of Russian businessmen in solidarity with the Syrian people," said Abdel Rahman al-Juraissi, president of the Saudi trade body.

France on Tuesday joined the United States in raising concerns that new massacres were being prepared in Syria as regime forces pounded for the eighth straight day the town of Al-Haffe.

"We share concerns about the preparation of new massacres," foreign ministry spokesman Bernard Valero said, adding that French officials were heading to Moscow for talks on the crisis on Wednesday.

The Yemeni army seized the Al-Qaida strongholds of Jaar and Zinjibar on Tuesday, officials said, more than a year after the jihadists captured most of Abyan province.

In the first major victories of a month-long offensive, troops backed by armored vehicles entered the town of Jaar after Al-Qaida gunmen withdrew during the night.

Armed "terrorists" kidnapped on Tuesday a group of Syrians travelling in two taxis on the road to Qusayr in the central province of Homs, the state news agency SANA reported.

"An armed terrorist group seized two collective taxis which were travelling on the Qusayr road," SANA said, saying an unspecified number of passengers were abducted.