'Large knife' causes major security scare and lengthy delays at Brisbane airport

A number of flights out of Brisbane International Airport are delayed this afternoon after a major security scare put the airport into lockdown.

Passengers on 11 flights had to be re-screened after a suspicious item was found on a passenger - either on their person or in their luggage.

The airport has not confirmed what the item was, but staff have told 9NEWS it was a large knife.

Hundreds of passengers had to cart their luggage back through the terminal to be re-screened causing lengthy delays.

The security risk is believed to have now been resolved and the AFP is investigating.

All passengers travelling in and out of Brisbane International Airport today are advised to expect delays.

One passenger travelling from New Guinea said he had been on the tarmac for an hour after landing.

"All we have been told is the airport is in lock down," Clive Young tweeted.

It comes as Sydney Airport experienced a technical glitch this morning, which has caused major delays to flights at the T1 and T2 terminals.