MOSCOW, Dec 31 - Two more people wounded by suicide bombings in the Russian city of Volgograd have died, increasing the death toll in the attacks to 33, Interfax news agency reported on Tuesday, citing the country's emergencies ministry.

The city's railway station was bombed on Sunday and a bus was ripped apart on Monday, raising fears of Islamist attacks on the upcoming Winter Olympics in Sochi, a resort on the Black Sea 700 km (450 miles) southwest.

Citing the ministry's regional spokesman, Interfax said that the number killed in the main rail station on Sunday rose by one to 18, while the bus bombing death toll rose by one to 15.

"At night in the Volgograd hospital, one victim of the railway explosion died, and the number of victims has increased to 18," said Dmitry Ulanov, a regional spokesman of the emergencies ministry, Interfax reported.

There have been no claims of responsibility for the attacks.