Both the idea and the effort to tackle the global food crisis are quite literally ‘far-fetched’ as the massive crops are growing from the seeds, which were fired into the space in China's rockets, where they orbited the Earth for two weeks.

Once they returned they were cultivated in hothouses in Guandong Academy of Agricultural Sciences, producing really monstrous specimens.

The 21 lb (10 kg) tomatoes, nine-inch chillies, 15-stone pumpkins and enormous watermelons can feed many more than their smaller cousins and may have more nutrients, scientists were quoted as saying by the Daily Mail.

The communist country has been experimenting with space plants since the 1980s.

Desperate to find new ways of feeding its 1.3 billion people, China launched 2,000 seeds in the most recent batch in 2006 on the Shijian 8 satellite.

Afterwards they were cultivated and the best specimens selected for further breeding.

The results included two-foot cucumbers and 14 lb (6kg) aubergines.

China says its giant fruit and vegetables have already been sold to Japan, Thailand and Singapore. There has also been interest from European agricultural companies, the report said.

"Conventional agricultural development has taken us as far as we can go and demand for food from a growing population is endless. Space seeds offer the opportunity to grow fruit and vegetables bigger and faster," researcher Lo Zhigang was quoted as saying in the report.

However, the scientists could not explain why time in orbit causes the seeds to mutate. But they suspect exposure to the cosmic radiation that bombards spacecraft in orbit, as well as microgravity, could play a part.

"We don't think there's any threat to human health because the genes themselves do not mutate, just their sequence changes," he said.

Citing a possible advantage that the monstrous crops had over genetic ones, Zhigang said, "With genetically-modified crops you have seen environmental problems because they have added genes that can damage other organisms. But with space seeds they don't gain genes, they can only lose them."

He also claims the Vitamin C content in some vegetables is nearly three times higher while that levels of zinc are also boosted.