David Miranda is challenging the legality of his detention at Heathrow Airport, his lawyers have said.

Solicitors for Miranda, partner of Guardian journalist Glenn Greenwald, have written to the Home Secretary and Met Police commissioner for assurances that "there will be no inspection, copying, disclosure, transfer, distribution or interference, in any way, with our client's data pending determination of our client's claim", law firm Bindmans LLP said.

Miranda was detained at Heathrow Airport under Schedule 7 of the Terrorism Act 2000 as he changed planes on a journey from Berlin to his home in Brazil.