has issued an urgent warning to passengers travelling from Heathrow and Gatwick Airports.

The airline warned drivers of major upcoming travel disruptions due to closures on the M25 and A3 in March and April.

The M25, which circles Greater London, will be fully closed in both directions for two weekends in March between junction 10 and 11, starting at 9:00pm on Friday until 6:00am on Monday.

Closures will be in place from March 7 until March 10, and March 21 until March 24, which are expected to increase the risk of traffic congestion on alternative routes.

British Airways advises passengers to consider alternative routes and allow extra travel time, while

at junction 10, which happens to be the busiest stretch of the road, will allow old bridges to be demolished and removed.

In April, the A3 will also be partly closed, with more closures expected in the following months.

The A3 will be fully closed in both directions between junction 10 and the Painshill roudabout from 9:00pm on Friday April 11 until 6:00am on Monday April 14.

In a statement, British Airways said: "We strongly advise you to plan your journey in advance and allow for extra time to reach the airport."

The M25 carries 15 percent of the UK's motorway traffic, equivalent to 200,000 vehicles a day, according to Skansa which handles construction for the road.