Britain has an "absolute veto" over any plans for a European Union army, Defence Minister Michael Fallon said Wednesday, ahead of a bitterly-fought referendum on the country's EU future next week.

Reports that EU foreign affairs supremo Federica Mogherini was proposing such a force have raised hackles in Britain where the "Brexit" campaign appears to have a slight lead, promising to end all interference from Brussels.

"Britain has an absolute veto towards any move towards a European army and that is not being proposed," Fallon told reporters on the sidelines of a NATO defence ministers meeting in Brussels.

"Armies are central to the sovereignty of member states and I don't hear any support from France or Germany. I don't see anyone who wants to see their troops controlled from Brussels," he said.

Fallon said the focus was firmly on cooperation between EU member states, as shown by efforts to curb illegal migrant flows or enforcing an arms embargo against anti-government rebels in Libya as just approved by the United Nations.

Brexit flotilla sails into London
London (AFP) June 15, 2016 - A Brexit flotilla of fishing boats sailed up the River Thames into London on Wednesday with foghorns sounding, in a protest against EU fishing quotas by the campaign for Britain to leave the European Union.

AFP journalists at the scene saw around 20 vessels near Tower Bridge, with signs including "Leave, Save Our Country" and "The Only Way is Brexit".

"Let's put the great back into Britain, vote out and be great again," read another banner on a boat.

Smaller dinghies with "IN" signs could also be seen on the Thames protesting against the flotilla, which was also jeered from the river bank by pro-EU supporters.

Rocker-turned-activist Bob Geldof was on one of the pro-EU boats, blasting out the song "In With The In Crowd" from a large on-board sound system.

The protest, organised by the "Fishing For Leave" campaign, was joined by UK Independence Party (UKIP) leader Nigel Farage and some of the boats were due to sail past the Houses of Parliament later on Wednesday.

"EU membership has destroyed our industry," Farage said in a statement, before boarding a barge decked out with Union Jack deckchairs and flags.

"Today's flotilla is not a celebration or a party but a full-throttled protest. We want our waters back," he said.

Environmental group Greenpeace accused Farage of "cynical opportunism" and said the problems of the fishing industry were due to the quota system devised by the British government not the EU.

"Quitting the EU will only condemn the industry to years of wrangling over new fisheries agreements, with no guarantee of a better deal for fishers or stronger protections for our seas," it said.