PLANS to build a cable car linking the Royal Docks with North Greenwich could be delayed after Boris Johnson ordered a safety review.

Opponents of London City Airport expansion had warned the link would pass through the airport’s public safety zone, possibly putting passengers at risk.

Planning chiefs at Newham Council - and their counterparts in Greenwich - have already granted planning permission for the scheme.

But it is now on hold while an investigation is carried out by the National Air Traffic Service.

The review - which is due to conclude next month - could deal a blow to Mayor Johnson’s plans to have the cable car up and running before the 2012 Olympics.

A City Hall spokesman said: “The Mayor has received letters suggesting that further safety analysis of the cable car application be carried out in relation to the expansion of City Airport.

“To be certain these concerns are addressed he has asked the boroughs to withdraw their referrals while TfL commission a National Air Traffic Services safety assessment.

“The results of that will be given to the boroughs for their consideration.

“They would then be able to refer their applications back to the Mayor’s Office asking him to approve a cable car that would provide a further much needed river crossing in the east of the city.”