A Ukrainian journalist held for several months by kidnappers in Syria is safe in Damascus after fleeing from her captors on Monday, her family said.

Ankhar Kochneva, an Arabic speaker who was working as an assistant for Russian media, was kidnapped in early October. She has reportedly said she was held by opposition forces who treated her poorly.

Thousands of Ukrainians protested in Kiev Monday against "political repressions" by the government of President Viktor Yanukovych as he flew to Brussels for a key Ukraine-European Union summit.

About five thousand protesters marched through central streets of capital Kiev before assembling on the main square, in a strong response to demonstration appeals by three opposition movements.

Armed pirates who stormed an oil service ship in southern Nigeria have kidnapped six foreigners and demanded a $1.3 million ransom for their release, police told Agence France Presse.

"Three of those abducted are from Ukraine, two from India, one from Russia," Bayelsa state police spokesman Fidelis Odunna said of the Sunday attack.

At least four people died when an Antonov AN-24 plane with dozens of football fans on board made an emergency landing Wednesday in the eastern Ukraine city of Donetsk, officials said.

"Most passengers have been rescued. Right now, we have four dead," local governor Andrey Shyshatsky told reporters at the airport.

French construction firms Vinci and Bouygues said Wednesday they had evacuated as a precaution around 80 employees from the Chernobyl nuclear power plant in Ukraine after a section of the roof collapsed.

The two companies are working on constructing the sarcophagus structure covering the reactor that exploded in 1986 in the world's worst nuclear disaster.

A section of the Chernobyl nuclear power plant in Ukraine has collapsed under the weight of snow but there were no injuries or any increase in radiation from the reactor that exploded in 1986, the country's emergency agency said Wednesday.

"The preliminary reason for the collapse was too much snow on the roof," the agency said, adding that the radiation situation is "within the norm" and nobody was harmed in Tuesday's incident.

About 20 opposition lawmakers have spent the night in the Ukrainian parliament chamber after blockading it in a voting dispute.

Deputies from the opposition Udar (Punch) party, led by world heavyweight boxing champion Vitaly Klitschko, spent the night from Tuesday to Wednesday in the parliament chamber.

Ukraine and the global oil giant Royal Dutch Shell signed Thursday a $10 billion shale gas production sharing agreement aimed at helping the ex-Soviet nation ease its dependence on Russia.

The deal was signed in the presence of Ukrainian President Viktor Yanukovych by Shell CEO Peter Voser and Ukrainian Energy Minister Eduard Stavitsky on the sidelines of the World Economic Forum in Davos, a gathering of the world's business and political elite.

Ukraine's jailed former prime minister Yulia Tymoshenko on Tuesday denied she was behind the killing of a powerful lawmaker in 1996, calling the murder charge against her "hysteria".

"I can state clearly and unambiguously that I have nothing to do with the tragic murder of Yevgen Shcherban in 1996, and this will be proven in international courts and in the courts of other countries," Tymoshenko said in a statement read to journalists by her lawyer Sergiy Vlasenko.

Prosecutors on Friday accused Ukraine's jailed former prime minister Yulia Tymoshenko of organizing the 1996 murder of a powerful lawmaker and warned that a guilty verdict could put her behind bars for life.

Prosecutor General Viktor Pshonka said the fiery 52-year-old has been informed by prosecutors she and another former prime minister detained in the United States are now formal suspects in the murder of deputy Yevgen Shcherban.