Controversial plans for an island airport in the Thames Estuary off north Kent could be feasible, it has been reported.

The £40billion project – dubbed "Boris Island" – is the idea of London Mayor Boris Johnson.

A report in the Sunday Times suggested that a leading civil engineer commissioned to examine whether it could be built has concluded that it could – and be completed within 10 years.

The official report by Douglas Oakervee, who was behind Hong Kong's international airport, is due to be published and presented to the Mayor in three weeks.

Before that, Mr Oakervee is to discuss the initial findings with a panel of experts at the Institution of Civil Engineers on Wednesday.

According to the Sunday Times, Mr Oakervee is said to have determined that a four-runway airport across two islands, linked to the mainland terminals by bridges or tunnels, could be built.

The idea of a island airport has been universally condemned in Kent, with politicians from all parties and local councils and environmental groups saying it is a non-starter.

Mayor Johnson is at odds with his own party's policy on aviation, which sets out an expansion of regional airport capacity using high-speed rail links to major cities.

Kent County Council says it would prefer to see greater use of Manston Airport in Thanet.