Senior MP Keith Vaz is to write to the Metropolitan Police to seek clarification on why the partner of Guardian journalist Glenn Greenwald David Miranda was held and questioned by officers while travelling through Heathrow.
Speaking on BBC Radio 4's Today programme, Mr Vaz said:"What needs to happen pretty rapidly is we need to establish the full facts.
"Now you have a complaint from Mr Greenwald and the Brazilian government - they indeed have said they are concerned at the use of terrorism legislation for something that does not appear to relate to terrorism - so it needs to be clarified, and clarified quickly.
"What is extraordinary is they knew he was the partner (of Mr Greenwald) and therefore it is clear people who are directly involved are being sought but also the partners of those involved".
More top news
Two police officers helping to guard diplomats have been sacked for sharing pornographic images on their mobile phones.
A 32-year old man from Hampton has been jailed for five years historic sexual assaults in the late 1990s.
A teenager who was mistakenly released from prison after he was arrested on suspicion of attempted murder has been detained by police.