Six of the seven people arrested on Brighton's Palace Pier this week were immigration offenders, the Home Office confirmed last night.

The six, all in their 20s, were all being held at a detention centre near Heathrow Airport and could be deported.

The seventh was originally held at a police custody suite in Brighton and has now been transferred to the Heathrow centre while officials continued their investigation.

A spokesman said: "This case has proven a little more complex but should be resolved soon."

The pier was closed for three hours on Tuesday during the raid by immigration officers and police.

The Noble organisation, which owns the pier, last night questioned the motive for such a large-scale operation. They suggested it could have been connected to the police shooting of Brazilian Jean Charles de Menezes at Stockwell Tube station after the July 7 suicide bombings in London because most of those arrested on the pier are Brazilian.

Noble director David Biesterfield said only one of the seven arrested was employed directly by the pier and the company's employment books were found to be "thorough and professional".

He said: "We maintain our view that the whole thing was massively overplayed."

He claimed the pier had been the victim of "Government spin", adding: "We were struck by the fact the Immigration Service had two press officers in attendance."