8 December 2011 Last updated at 17:57 ET

Oxford Circus Tube station evacuated by London police

The station serves three Tube lines in the heart of the West End of London

A group of more than 200 DR Congo demonstrators have caused an emergency evacuation of Oxford Circus Tube station in central London, British Transport Police (BTP) has said.

They set off a passenger alarm on a train they had boarded following an earlier protest in Whitehall over their country's political situation.

About 30 police officers were sent into the station, which was closed for half an hour at about 21:30 GMT.

No arrests were made, BTP added.

The group joined the Victoria Line at Green Park after gathering in Whitehall, police said, but became rowdy at Oxford Circus, which was the next stop northbound.

Election violence

After the station was cleared, officers arranged for an empty Tube train to be brought in and all of the protesters were led to this, they added.

The demonstrators were transported to Seven Sisters station and the Metropolitan Police arranged for them to be dispersed from there.

A general election is being held in the African nation of DR Congo, where there have been violent clashes as opposition supporters alleged the polls were marred by fraud.

The emergency saw several police vans parked at the corner of Oxford Street and Regent Street.

The station serves the Bakerloo, Central and Victoria Lines and it has now reopened to passengers.

It had been busy with Christmas shoppers throughout the evening, with retailers opening later, as is traditional on a Thursday.