The Home Office has ordered an official review of Britain's immigration figures after new exit checks at the borders found there may be fewer immigrants in the country than previously thought.

The Government will reveal on Thursday that new border checks introduced last year found 97 percent of international students - one of the biggest groups of immigrants - left after finishing their studies.

It had previously been thought that tens of thousands of international students remain in the country illegally and the disclosure that the majority are leaving casts serious doubt on the reliability of the official immigration statistics.

The immigration figures are based on relatively small-scale passenger surveys at airports, even though they are one of the most politically sensitive pieces of data which dominated recent election campaigns and the Brexit referendum.