The British MotoGP round is among the events now under threat following Thursday's announcement that circuit boss Simon Gillett is being sued by owner Tom Wheatcroft over 'unpaid rent'.

Wheatcroft & Son Limited awarded Gillett's company Donington Ventures Leisure Ltd a 150-year lease of the circuit in January, 2007.

"It is with great reluctance that we have taken this decision," said Kevin Wheatcroft. "Donington Ventures Leisure Ltd owe us nearly ?2.5 million in rent dating back to September, 2008.

"Despite receiving numerous re-assurances over a number of months, they have consistently failed to meet their financial obligations under the terms of the lease.

"We have held off taking legal action for as long as possible, but have been left with no choice but to commence proceedings to recover the outstanding rent and forfeit the lease."

This year's MotoGP event, due to take place on July 26, will be the last at Donington before a switch to Silverstone.

By contrast, Donington has been awarded a ten-year contract to replace Silverstone as host of the British F1 Grand Prix from 2010.

Gillett was supposed to announce how the ?100 million Donington development needed for F1 would be funded at the end of March, but no announcement has yet been made.

Other major two-wheel championships that will be watching the Donington developments closely include BSB (scheduled for May 25) and WSBK (to be held on June 28).