All flights from Heathrow Terminal 3 were grounded due to a "security issue", an airport spokeswoman said.

No flights were able to take off for a "short time" on Friday morning after reports of a "suspicious package", a Metropolitan Police spokeswoman said.

Passengers said aircraft scheduled to depart were searched by armed police as they waited on the runway.

Tim Chambers, a passenger on a BA flight to Bilbao, said the captain on his flight had told passengers the delays were due to an incident involving a man said to have grabbed his bag and run through security.

He said his plane was held on the tarmac for two hours due to a suspected "security lapse", with each plane due to depart being searched by armed police.

While it was initially feared the passenger had run back on to the airside area of security from arrivals, it was later confirmed this was not the case.

Flights have since resumed.

An airport spokeswoman said: "Departures were suspended for a short time from Terminal 3 due to a security issue.

"We are very sorry to any passengers whose journeys are affected. The safety and security of our passengers and colleagues is paramount."