And it is only a matter of time before the creatures – which can inflict a powerful and potentially fatal sting – are found washed up on local beaches.

The warning that the stingers are getting closer comes after 10 of the huge jellyfish were washed up just a few miles down the coast in West Sussex, around West Wittering and Bracklesham Bay.

It is the latest in a series of such discoveries along the south coast.

A walker discovered the first of the creatures – whose tentacles can grow up to 165ft long – lying on the beach on Saturday evening, and another nine have now been found.

Chichester District Council has put up notices to warn bathers, and has contacted local hospitals to alert staff there about potential problems.

If touched the jellyfish can cause an agonising sting, seizures, breathing problems and at worst can send the victim into anaphylactic shock, where people can suffocate to death as the airways close.

Peter Richardson, from the Marine Conservation Society, said: 'Absolutely, there's a good chance you will get them.

'South westerly winds have blown them out of their waters and into inshore waters.

'They are gradually getting blown along the south coast. I would not be surprised to see them washed up in Portsmouth.'

In Atlantic waters, man-of-war colonies are usually found in the Florida Keys and in the Gulf Stream, the Gulf of Mexico, and the Caribbean, but strong winds have been blowing them towards the English Channel.

Earlier this month the jellyfish were found on the South West coast around Cornwall, Devon, and Dorset.

Mr Richardson added: 'If they were on the beach, I would not let my children anywhere near them and I wouldn't let them in the water.

'They are pretty obvious. They have a big float that looks like a bright-blue Cornish pasty-shaped balloon and dark blue tentacles.

'They are very beautiful. That is part of the problem, though, as children think they have found something unusual and end up touching them.'

Portsmouth City Council said it was not yet issuing any warnings to bathers.

Chichester Harbour Conservancy said it was monitoring the situation, but had no plans yet to issue any warnings.