A German inventor has admitted that spray-on condoms may never hit the shelves after his team were unable to overcome technical problems.

Jan Vinzenz Krause of the German Institute for Condom Consultancy made headlines across the world when he announced his pioneering design in 2006.

Krause promised the spray-on condom would offer a better, safer fit for men of all sizes.

"We thought why not come up with a condom that fits the man rather than vice versa? This would represent a revolution in the condom market," said Krause.

"With our technology we could spray a condom on an erect elephant," he added.

Krause filed for a patent for the latex spraying system he invented and had hoped to have it on sale this year.

But the project hit problems and may never reach the market, according a statement on his website.

"Whether we can solve the technical problems, and whether the advancement of the idea is financially viable, remains uncertain," he wrote.

Spray-on condoms ignited a wave of online interest recently after being featured in the US forensics show CSI and getting a mention on the BBC's Friday Night with Jonathan Ross.

Demonstrating it on a model, CSI character Lindsay Monroe said: "Simply apply like so. Allow a few moments for maximum drying time and, boom. Instant condom."

Can You Hear Me Now?, the CSI:NY episode featuring the condom, was shown in the US in September 2007 but has not yet been aired on British terrestrial TV.