Syria's main opposition group Wednesday urged the international community to create humanitarian corridors in the country for vital aid delivery but a plea for backing from Moscow went unmet.

At a news conference in Paris, the Syrian National Council said it would attend Friday's Tunis meeting of countries known as the "Friends of Syria" and ask for safe passage zones in which relief convoys can operate.

More than 6,000 people have died in nearly a year of upheaval as the government has sought to snuff out a revolt that began with peaceful protests but has since seen military deserters take up arms against the regime.

SNC spokeswoman Bassma Kodmani in a statement to be given to Friday's meeting demanded "international assistance to respond to facts on the ground, specifically humanitarian assistance and a safe haven inside Syria."

She described three key areas which could be secured to provide help: one bordering Lebanon to assist the Homs area, one near Turkey to help the town of Idlib and one on the Jordanian border to help Deraa.

"Safe passages can be guaranteed by a commitment from Russia to force the regime to respect safe access for convoys," the statement said.

Moscow said it backed Tuesday's call by the International Committee of the Red Cross (ICRC) to set up a daily two-hour truce in Syria but opposed establishing humanitarian corridors.

The foreign ministry said Russia was growing "seriously concerned" about the humanitarian situation in Syria and was putting pressure on both President Bashar al-Assad and the armed opposition to halt the violence.

"We actively support the efforts of the International Committee of the Red Cross" to establish a truce, foreign ministry spokesman Alexander Lukashevich told a weekly press briefing. "It is presumed that this pause will be used to provide humanitarian assistance to the nation's population."

But another top official said Russia was not backing a call to set up actual humanitarian corridors for delivering assistance to flashpoints such as Homs because these would require support from foreign troops.

"Creating these corridors would hardly be effective," Deputy Foreign Minister Gennady Gatilov said.

"This would require special mechanism and forces and, logically speaking, this could lead to the use of force, should things go wrong."

Russia is a traditional ally of Assad's regime and, with China, last month vetoed a UN Security Council resolution criticising Damascus for its repression of the year-old popular revolt.

The SNC also said that after the apparent failure of an Arab League peace plan to resolve the crisis, the time had come for the international community to consider intervening militarily in Syria as it did in Libya.

"We were exploring every other option and waited for the Arab League to exhaust all these options. None of this has given results," Kodmani said.

"This may well be the only option. We are choosing between two evils: the evil of a military intervention and the evil of a civil war," she said.

The opposition group reiterated the need for safe passages following a meeting with ICRC head Jakob Kellenberger in Geneva later Wednesday.

The organisation's call for a daily two-hour truce was an "interesting option", Kodmani said, but she added that the ICRC's powers were limited and political action was what was needed to create safe havens.

"They chose to speak about time rather than space because it is in the range of what they can do as a humanitarian organisation," said Kodmani.

"Our call for serious involvement to bring in humanitarian assistance is one of the key demands that we will be taking to Tunis and that is for politicians, we do not make such demands on the ICRC.

"We can say that to increase the possibility of the ICRC and other humanitarian organisations to be able to work adequately we need political decisions and political mobilisation."

Kodmani said the world had not responded adequately to the crisis: "The people feel abandoned. They feel they are being let down by the world."

The "Friends of Syria" conference will gather top diplomats from the Arab League, Europe and the United States, along with the opposition, in a bid to boost international efforts to end the crisis in Syria.

Russia has denounced the meeting as one-sided and refused to attend. China has also refused to commit itself.