The US airline Delta is working with the FBI and officials in the Netherlands to find out how sewing needles entered in-flight meals.
The needles were found in sandwiches on four US-bound flights that left Amsterdam on Sunday.
Delta spokeswoman Chris Kelly said in an email to Reuters that the sandwiches were prepared by the airline's Amsterdam caterer, Gate Gourmet.
More top news
PM used a speech in Hamburg to say that the UK will not 'pull up the drawbridge and retreat from the world' but Europe must change.
It is set to remain unsettled into Saturday, becoming drier on Sunday.
The Independent has announced it is to cease publication and go online only from the end of March.