A Royal Navy warship is expected to arrive in Gibraltar after more than 40 Spanish boats were involved in a confrontation with the British authorities.

The Spaniards made an illegal incursion into British waters around the rock led by a group of around 38 fishing boats plus a small number of pleasure craft.

They were "corralled" by Royal Gibraltar Police, customs and military vessels close to an artificial reef created by the government of the British Overseas Territory.

Tensions between Britain and Spain over Gibraltar's dropping of concrete blocks to the sea floor creating a reef have escalated during the last fortnight. Spain says it was done to disrupt their fishing fleet.

Gibraltar says it was necessary to protect local fish stocks and that only one Spanish vessel was fishing the area before the reef was created. The expected arrival of HMS Westminster, a type 23 frigate, is not part of Britain's response to the growing row.

The vessel left Portsmouth naval base in Hampshire six days ago to join nine other vessels taking part in a pre-planned international training exercise called Cougar '13 in the Mediterranean and Gulf. Cougar '13 is a long-planned deployment involving four Royal Navy warships, the lead commando group from 3 Commando Brigade Royal Marines and elements of naval air squadrons.

The protest prompted calls for renewed efforts, involving the European Union, to solve the diplomatic dispute which has seen Madrid introduce additional checks at the border in protest, leaving workers and tourists facing hours in queues to get through.

Julie Girling, a Conservative MEP for Gibraltar, called the flotilla a "provocative attempt to stir things up yet again" by a government in Madrid facing allegations of corruption. "We need to find a way to make all this stop," she said.

"This has been an extended period (of border controls) and people seem to be worried that with the difficulties the Spanish Government has at home they are not going to stop, they are going to keep pushing. What we would like to see is the European Commission saying 'this is not proportionate'."

A diplomatic spat between Britain and Spain erupted when the Spaniards introduced additional checks at the border, suggesting that a 50 euro (£43.30) fee could be imposed on every vehicle entering or leaving Gibraltar through its fenced border with Spain. On Friday Prime Minister David Cameron raised the imposition of the extra checks with European Commission president Jose Manuel Barroso.