Eight women and 42 men -- mostly ethnic minority Tamils-- were deported by Britain's Border Agency, which chartered an aircraft to return them home after they failed in a bid for asylum based on their alleged risk of persecution.
"They are being questioned by police detectives," an airport official said without giving details.
In June, a group of 20 Sri Lankans were sent back from Britain, drawing criticism from international rights groups which expressed fears that the deportees were at risk of torture once they got home.
London-based rights group Amnesty International said at least one of the failed asylum seekers had tried to commit suicide at an airport detention facility in June following death threats he reportedly received.
Thousands of Sri Lankans, mainly ethnic Tamils, had sought refuge in the West and neighbouring India during the the decades-long war which pitched government forces against Tamil separatists.
Amnesty had said that the end of the conflict two yea