Image caption Spain disputes UK sovereignty over Gibraltar

UK Foreign Office officials have met the Spanish ambassador to raise "serious concerns" about a Spanish ship off Gibraltar.

The Royal Navy challenged a Spanish state vessel, the RV Romon Margalef, after it had conducted more than 20 hours of surveying.

The Foreign Office said the ship's presence on Monday and Tuesday had been a "significant incursion".

At the meeting it also highlighted "unacceptable" border delays.

The Ministry of Defence (MoD) said the Spanish vessel had come within 250 metres of the entrance to Gibraltar Harbour and had been close to other ships at anchor.

The move prompted the Royal Navy's Gibraltar Squadron's fast patrol boats HMS Sabre and HMS Scimitar to challenge the RV Ramon Margalef's presence.

The MoD said no-one was injured and no equipment or vessel was damaged.

An urgent question on Gibraltar will be asked in the House of Commons later by Conservative MP Bob Neill and will be answered by Foreign Office Minister Mark Simmonds.

'Needling away'

Media playback is unsupported on your device Media caption Fabian Picardo: This is an issue of sovereignty in an area where sovereignty matters

Matthew Rycroft, the acting permanent under-secretary at the Foreign Office, met the Spanish ambassador to the UK, HE Federico Trillo, on Tuesday to discuss the incident.

It is the third time the Spanish ambassador has been publicly summoned over the conduct of Spain towards Gibraltar since Spanish Prime Minister Mariano Rajoy's government took office in December 2011.

During the meeting, Mr Rycroft also raised the border delays which the Foreign Office said continue to affect Gibraltarians and tourists, as well as large numbers of Spanish commuters benefiting from employment in Gibraltar, on a "near-daily" basis.

On Tuesday evening the Royal Gibraltar Police warned of lengthy queues at the border.

The police said on Twitter: "At present we have 6 lanes of traffic with the tail end of traffic reaching the South Barrier. EQT of 2 hrs"

David Lidington, the UK's Minister for Europe, has told MPs that the UK has made repeated diplomatic protests over incursions in recent months.

Mr Lidington said Spain had increased unlawful incursions by its state vessels into UK territorial waters from about five per month to about 40 per month.

"We stand ready to do whatever is required to protect Gibraltar's sovereignty, economy and security," Mr Lidington said.

"We believe that it is in the interests of Spain, Gibraltar and Britain to avoid incidents such as this that damage the prospects for establishing dialogue and co-operation."

We stand ready to do whatever is required to protect Gibraltar's sovereignty, economy and security David Lidington, UK's Minister for Europe

He said: "This comes only two weeks after dangerous manoeuvres by a Spanish Guardia Civil vessel in the vicinity of Royal Navy vessels in British waters put lives at risk and resulted in a minor collision".

Gibraltar's Chief Minister Fabian Picardo told BBC Radio 4's Today programme Spain was "needling away at the UK and Gibraltar by "taking such action".

According to the United Nations Convention on the Law of the Sea, the waters around Gibraltar are indisputably British territorial waters, Mr Lidington said.

However, Spain disputes UK sovereignty over Gibraltar, a limestone outcrop known as the Rock near the southern tip of the Iberian peninsula, which has been ruled by Britain since 1713.

Spain imposed additional strict controls at the border with the British territory after a row broke out in July over the creation by Gibraltar of an artificial reef in disputed waters.

Last week the European Commission ruled checks by Spain at its border with Gibraltar did not break EU laws but has also written to the UK and Spain with recommendations to avoid future delays at the border. The UK still says the "politically motivated" checks were unlawful.

Correction 13 December 2013: This story has been amended to clarify that it is the UK government's view that the waters around Gibraltar are 'indisputably British territorial waters'