The road that links London to Heathrow Airport has been closed after a crack was discovered in a viaduct.

The M4, which has been shut between junctions one and three, is expected to reopen on Thursday.

Restrictions have been put in place on vehicles weighing more than 7.5 tonnes since hairline cracks were first dicovered in March

The Highways Agency has confirmed that work is expected to be completed before the Olympic Games later this month, amid rising concerns.