A surprise security check of Hong Kong International Airport's restricted early this morning turned up 59 people, but no forged documents.

Immigration officers and representatives from the Police, Customs & Excise Department, Airport Authority and Aviation Security Company turned out for the 1am to 3am operation. They were on the lookout for forged passports and other criminal activity.

It was the seventh joint operation since the airport opened in 1998.

Immigration officers inspected travel documents to check for forgeries, Customs officers looked for restricted items, and the Police dealt with other crime-related matters.

The officers found 59 people inside the restricted area, but no forged documents.

The inspections deter the exchange of forged travel documents in the airport and prevent illegal immigrants from using Hong Kong as a transit point.

The departments and organisations conduct such operations regularly to uphold security.