The most powerful ships ever to sail in the Royal Navy will be forced to fly ageing Harrier jets because the replacement F35 Joint Strike Fighters (JSFs) will not be ready in time.

The first of two new aircraft carriers is due to enter service in 2014 and the government had planned to operate Britain’s next generation combat plane, the JSF, from the ships. However, it emerged on Tuesday that the Navy will instead initially have to operate the latest version of the Harrier jump jet, an aircraft first designed several decades ago.