The Foreign Office is investigating reports that a number of British nationals were killed in a suicide bombing in Afghanistan.
The explosion took place yesterday at a compound in the southern city of Kandahar which is shared by a number of foreign companies.
Reports suggest up to seven people have been killed, some of them British.
A spokeswoman for the Foreign Office said: "We have no information to confirm anything at the moment. Investigations are taking place."
The Ministry of Defence confirmed that no British military personnel had been caught up in the blast.
The explosion took place last night, just hours after a car bomb exploded outside a hotel in the city, injuring eight people.
A source close to the Afghan president told the Associated Press that three foreigners and three local soldiers were killed in the attack.
Ahmed Wali Karzai, the half-brother of President Hamid Karzai and an influential figure in Kandahar, told the news agency that several people were injured in the blast alongside the fatalities.
The impact of the bomb was felt up to 2.5 miles away, with windows being blown out across the city.
The compound targeted houses a number of workers for international contracting and security firms.
The Foreign Office said it was in contact with officials in Afghanistan in a bid to establish if British nationals were involved in the incident.
A spokesman for the department said: "We are aware of an explosion this evening in Kandahar. We understand that there are a number of internationals amongst the casualties but their nationalities have not yet been confirmed."
Development consulting firm Chemonics International has a strong international presence in the compound that was attacked.
A spokeswoman for the US-based company said no British or American nationals it employed had been involved in the incident.