A probe has been launched after passengers found sewing needles in sandwiches on four transatlantic flights to the US.

An FBI investigation follows the discoveries on four Delta Air Lines flights to Atlanta, Seattle and Minneapolis, from Amsterdam.

Flight attendants were alerted after the needles were found inside five turkey sandwiches.

One passenger on the Minneapolis flight was injured but declined medical attention. The sandwiches are believed to have been prepared for business class passengers, the Daily Telegraph reported.

After the discovery, a message was broadcast to all flights from Amsterdam, where food had been prepared by catering company Gate Gourmet.

The FBI’s Atlanta office has opened a criminal investigation into the matter, the agency said.

A spokesman for the airline said: “Delta is taking this matter extremely seriously and is cooperating with local and federal authorities who are investigating the incident.

“Delta has taken immediate action with our in-flight caterer at Amsterdam to ensure the safety and quality of the food we provide onboard our aircraft.”

Gate Gourmet said: “We take this matter very seriously, and we have launched our own full-scale investigation.”

The company added that it was “heightening our already stringent safety and security procedures, to prevent any recurrence”.