BBC World Service is based at Bush House, London
The expansion is a response to escalating tensions in the region following last week's attacks on the US.
BBC World Service Director Mark Byford said that the BBC World Service is a "vital lifeline" in the region and they needed to act to secure their broadcasts.
"Audiences, literally, depend on the BBC for impartial, accurate, trustworthy news and information," he said.
"In Afghanistan, with no television and no national newspaper, BBC radio is a main form of communication."
Reprisals
A Saudi-born militant - Osama Bin Laden - has been named as the key suspect behind the suicide attacks on New York and Washington.
He is thought to be in Afghanistan, sheltered by the Taleban regime.
Refugees have been pouring out of Afghanistan - fearing US reprisals - though neighbouring Pakistan has now closed its borders.
"Our expansion is a prime example of the BBC World Service responding to audience need and moving resources quickly to where it is needed most," said Byford.
BBC World Service plans to boost short wave transmissions in the region.
Output in Arabic, Pashto, Persian and Urdu, key languages in the region, is to be expanded.
The Arabic service has increased its broadcasts to become a 24-hour service, providing news bulletins throughout the night, and adding other long-form current affairs and analysis programmes.
Pashto, Persian and Urdu are increasing their online service, which includes access to audio broadcasts, for locals and nationals living elsewhere around the globe.
The BBC World Service broadcasts in 43 languages including English.