Russian space officials have set a deadline for 'N Sync star Lance Bass to pay for his place on a mission if he wants to fulfil his dream of becoming the next space tourist.

The boy-band singer must come up with the fee, believed to be about $20m (£13m), by Friday if he is to secure a place on a trip, a spokesman for the Russian space agency said on Monday.

The deadline follows weeks of wrangling and negotiations over whether Bass, 23, would take part in the next trip to the international space station in October.

A television series of Bass's exploits is planned

"The full sum provided for in the contract has not been transferred yet, and the deadline for its transfer expires very soon," the spokesman said.

Bass's representatives said the delay in making the payment has been due to problems with Russian bureaucracy and paperwork.

David Krieff, a television producer who hopes to film the trip, said three sponsors are willing to pay between $5m-$15m each (£3.2m - £9.8m).

Mr Krieff has not identified them but said they include a "huge soft drink" manufacturer and referred to a conglomerate "like Procter & Gamble".

An earlier deadline for payment had passed on 13 August, a Russian space agency official said at the time.

'Kicking butt'

The singer will continue training in Star City, outside Moscow, until Friday.

Mr Krieff earlier said Bass was "kicking butt in every way" and that "everybody loves him there".

He will then travel back to the United States, where Nasa is planning for Bass and his cosmonaut crew to visit the Johnson Space Center in Houston for a week of training.

Bass would become the third "space tourist" and the youngest person to go into space so far.