A multibillion-pound electronic surveillance system operating on the border between Northern Ireland and the Republic would not change if Britain exited the EU, Ian Paisley Jnr has said.

At present every vehicle number plate is read and the number of crossings noted to protect security, according to the North Antrim MP, as part of an electronic barrier extending around the limits of the UK.

The senior Democratic Unionist Party politician said: "The current Northern Ireland border is not a soft border, the current Northern Ireland border is an electronic border.

"Every single vehicular movement on the border, every single person movement on the border, is electronically recorded.

"So for example ... you can have an electronic readout of the people who cross the border, the number plates which cross the border, the multiple crossings those number plates make."

Opponents of the Brexit have raised concern about the reintroduction of physical barriers between Northern Ireland and the Republic in the event of a withdrawal from the EU.

Mr Paisley said electronic surveillance already substituted for physical barriers and was done for security reasons.

"It is a multibillion-pound operation, probably one of the most advanced border movement management systems in Europe. It is quite similar to Switzerland in many ways."

Mr Paisley added: "There is a very highly priced and expensive border operation, there is nothing to suggest that that would change in any way on Brit exit."

He is a member of the Northern Ireland Affairs Committee of MPs at Westminster, which is conducting an inquiry into the impact of Brexit on Northern Ireland.

Queen's University Belfast witness Dr Cathal McCall noted the surveillance was done across coastal limits of the UK and acknowledged extensive information sharing between the Garda and PSNI.

Cameron says progress has been made on reforms

Meanwhile, British Prime Minister David Cameron has said securing the package of proposed reforms to Britain's relationship with the EU will need hard work and patience but real progress has been made.

Mr Cameron told MPs in Westminster the plans put forward by Brussels were the strongest ever achieved on freedom of movement rules.

But he admitted the details would need to be pinned down during the course of the "intense" round of negotiations that will be held in the run up to the meeting of EU leaders later this month.

Mr Cameron said: "I believe we are making real progress in all four areas but the process is far from over.

"There are details that still need to be pinned down and intense negotiations to try and agree the deal with 27 other countries.

"It will require hard work, determination and patience to see it through but I believe that with these draft texts and with all the work we have done with our European partners Britain is getting closer to the decision point."

Labour leader Jeremy Corbyn confirmed that Labour remained committed to keeping Britain in the EU but dismissed Mr Cameron's re-negotiation as a "Tory Party drama".

"For all the sound and fury, the Prime Minister has ended up exactly where he knew he would be making the case to remain in Europe which was what he always intended despite a renegotiated spectacle choreographed for TV cameras over the continent," he said.