West Ham United's plans to convert the London Olympic stadium into a football ground could cost an extra £130 million.

The Mail on Sunday says close to £500m of public money was spent to build the venue and it took seven years of wrangling over its post-Games use before last week's announcement that West Ham had clinched it.

Plans boasted of a 'state-of-the-art seating solution' to ensure the stadium offers 'a world-class viewing experience for watching football'.

But stadium experts have pointed to the cost of installing retractable seats into the stadium to ensure the stadium can be easily transformed back to athletics mode. They believe the seats could add £130m to the cost.

The idea of installing retractable seating was rejected in the early planning stages of the stadium on the grounds of cost. So estimates of £150m to convert the stadium to its post-Games use are likely to be way short of the final figure.