Russia's weather and emergency officials soothed fears of Moscow residents Thursday with statements that green-tinged clouds over the capital were not an alien invasion, but tree pollen.

"Today Muscovites felt like characters in a disaster film about an alien invasion: people living in the southwest of the city saw that the sky had been colored green," said Russia's weather service on its website.

Russian Communists on Saturday protested plans to create a NATO cargo transit base on the Volga river, calling it an "ulcer" on Russia's territory.

About 1,500 people gathered in the central Pushkin Square in Moscow with red balloons, flags and banners, while smaller rallies were held in many regional cities to protest what Communists call a "betrayal" of national interests.

Fifteen people died Tuesday when a night time fire tore through a two-story Moscow market warehouse that was being used by migrant workers from a former Soviet republic as a temporary residence.

"Fifteen people died. They were migrant workers. We are trying to confirm which (ex-Soviet) republic they came from," a Moscow emergencies ministry spokesman told Agence France Presse.

The date and place for talks between world powers and Iran on Tehran's controversial nuclear program have not yet been set, Russia said on Monday.

"The date and the place of the meeting have not been definitively set," Sergei Ryabkov, deputy foreign minister, told the Interfax news agency.

Russian authorities Sunday cordoned off Moscow's iconic Red Square and arrested 55 opposition supporters to prevent a rally against Vladimir Putin, who is due to take up his old Kremlin job.

All access roads to the central square were blocked off, an Agence France Presse reporter said, adding that police arrested dozens of supporters of the "Russia Without Putin" movement.

Syria has responded afresh to U.N.-Arab League envoy Kofi Annan on his six-point proposals to end the crisis in the country, the former U.N. chief's spokesman said Monday.

"The Syrian government has formally responded to the Joint Special Envoy for Syria, Kofi Annan's 6-point plan, as endorsed by the U.N. Security Council," he said in a statement. "Mr. Annan is studying it and will respond very shortly."

Progressive Socialist Party leader MP Walid Jumblat praised on Monday the Syrian Muslim Brotherhood’s statement on the developments in their country, saying that it reflected the Sunni population’s openness to regional changes.

He said: “The Muslim Brotherhood demonstrated moderation, diversity, and equality.”

Russia has arrested two suspected murderers who are believed to have eaten body parts of at least seven victims, investigators and media reported Monday.

A suspected serial killer in the town of Penza, some 560 kilometers (348 miles) southeast of Moscow, is believed to have "killed at least six people," the Investigative Committee said in a statement.

U.N.-Arab League envoy Kofi Annan's visit to China to discuss the crisis in Syria, initially scheduled for this weekend, will take place on Tuesday and Wednesday, the Chinese foreign ministry said.

Annan's spokesman had said on Friday he would visit Beijing and Moscow at the weekend for talks in two countries criticized for resisting global efforts to condemn Syrian President Bashar Assad.

U.N.-Arab League envoy Kofi Annan will travel this weekend to Moscow and Beijing to discuss the crisis in Syria, his spokesman said Friday, adding that a team sent to Damascus has returned.

The team is back after "three days of intensive talks with Syrian authorities on urgent steps to implement" Annan's proposals on halting the violence.