Thousands of air passengers were held up at London airports early on Wednesday morning after thick fog caused more than 80 flights to be cancelled or delayed.

About 60 flights were cancelled at Heathrow due to poor visibility, and dozens of departures were delayed.

More than 20 flights were cancelled from London City Airport and flights from Gatwick were running late.

The Met Office said the dense blanket of fog was set to clear later in the day but warned that travel disruptions could continue into the afternoon.

Among airlines affected by the cancellations and delays were British Airways, Air France and Dutch carrier KLM. – Reuters