Marine One lands as US President Barack Obama arrives at Winfield House, the U.S. Ambassador's residence, where he will stay in London

President Obama will be joined by wife Michelle tomorrow ahead of their meeting with the Queen

US Secret Service agents watch on as the president and his entourage walk into into Winfield House, the U.S. Ambassador's residence, following a quick helicopter flight from Stansted Airport

Obama is likely to suggest Britons should vote to stay in the bloc to preserve Britain's wealth, its 'special relationship' with the United States and the cohesion of the West.

Speaking prior to his arrival, Ben Rhodes, Obama's deputy national security adviser, said: 'As the president has said, we support a strong United Kingdom in the European Union.'

The US government - and many US banks and companies - fear a Brexit would unleash market turmoil, diminish British clout, undermine London's status as a global financial capital, cripple the EU and undermine Western security.

The president's intervention in the so-called 'Brexit' debate has already sparked criticism from some who say he is meddling in Britain's business.

Air Force One touched down at Stansted Airport shortly after 9.30pm on Thursday after visiting Saudi Arabia where Obama held talks with King Salman.

Upon arriving, the president waved as he exited the plane before being greeted on the tarmac.

He was then ushered into the presidential helicopter Marine One before being taken from the airport.

Police were seen increasing security in and around the airport throughout the day.

Armed officers were stationed around the terminal and outer fencing to ensure the president touchdown safely.