A CITY defence expert believes the visit of HMS Ocean to Brazil could help to "buy influence" if Argentina contests oil rights off the Falklands.

Ian Ballantyne, editor of Warships International Fleet Review, believes the visit to South America will also help to promote UK technology and engineering to the rising naval power.

The Devonport-based helicopter carrier is operating off Rio de Janeiro taking part in amphibious exercises with the Brazilian navy and marines and conducting high-profile diplomatic engagements.

But one Plymouth-based Royal Navy source has questioned the reason behind the visit of Government minister Gerald Howarth to the warship, given that he is responsible for defence sales.

It comes at a time when speculation has suggested the possible scrapping of the UK's amphibious fleet to plug Ministry of Defence spending.

During the mid-1990s Brazil bought four Devonport-based Type 22 frigates — HMS Brilliant, HMS Brazen, HMS Broadsword and HMS Battleaxe — for $170 million.

Brazil also bought a number of mine warfare patrol vessels in the 1970s from the UK, as well as new frigates.

Mr Ballantyne said he also believes HMS Ocean's visit to Brazil is part of the coalition Government's policy to extend economic and trade links beyond the US and Europe.

"India [which Prime Minister David Cameron visited recently] and Brazil are two nations which are rising naval powers," Mr Ballantyne said.

"It could buy influence if Argentina does contest oil rights around the Falkland Islands.

"Oil exploration is probably to go ahead and one day it could be very important.

"If Argentina is going to contest the rights it's always a good idea to make friends with its neighbours like Brazil and Chile.

"The trade is important because it feeds into the diplomacy of it all.

"It's a good way of building trust. It could buy diplomatic influence."

During the visit to Rio, HMS Ocean will host a UK Trade and Industry exhibition and a bilateral security seminar.

This will culminate in the signing of a UK/Brazil Defence Cooperation Agreement.

A naval source in Plymouth added: "I think it's obvious that Ocean is there with a view to it being sold to the Brazilians.

"It wouldn't surprise any of us if that was the case — especially with the carriers currently being built."

But Captain Keith Blount, HMS Ocean's commanding officer, said: "This visit to Rio is very important for the Royal Navy and we are extremely proud to be working alongside the Brazilian navy and marines, enhancing our ability to operate together anywhere in the world while also demonstrating the UK's commitment to the region."

A Ministry of Defence spokesman also rejected the claim, stating: "HMS Ocean will run quite comfortably until 2030 when she is due to be decommissioned.

"This visit is more about supporting British trade and industry.

"We do not know the answers from the Strategic Defence and Security Review and we could go for some other sort of amphibious capability.

"However, we are certainly not going to Brazil with the mindset of selling Ocean to the Brazilians."