SECURITY has been tightening up around Blenheim Palace in recent days in anticipation of a visit from President Donald Trump.

The controversial US leader and the First Lady, Melania, will be hosted by Prime Minister Theresa May for a black tie dinner at the palace tomorrow night.

Extra security has been spotted on the site as Thames Valley Police continues to step up its efforts at the Woodstock palace.

The Oxford Times:

Aircraft, believed to be American military, was spotted in the skies above the county earlier this week.

The aircraft, an MV-22 Osprey flanked by VH-60 helicopters, flew above Begbroke on Monday and is understood to have been part of the Presidential Transport Squadron, scouting the area.

An airspace restriction will be in place above the palace throughout the day, with a Civil Aviation Authority Statement reading: "The restrictions apply to all airspace users including drones.

"Pilots and drone operators are reminded to take account of the restrictions when planning flights. The restrictions are in place for the safety of all aircraft."

Three truckloads of police parked up in the town centre this morning as the police presence stretched beyond the palace grounds for the first time this week.

Security staff were spotted giving the town's pubs and businesses a list of numbers to call if they noticed any suspicious activity.

New heavy duty steel barriers and fences could be seen being installed around the site.

The Oxford Times:

Police let people know of an increased force presence at locations forming part of the visit, including Blenheim Palace, with hundreds of protestors expected to demonstrate outside from 5.30pm to express their objection to President Trump's politics.

The palace itself finally broke its silence on the event - but remained tight-lipped on detail and did not mention President Trump. In a statement, the palace said it was closed for a 'significant Government event'.

It added that it was working closely with the British and US Governments to ensure the event goes 'as smoothly as possible'.

Meanwhile, coach loads of tourists were turned away from the palace on Wednesday morning, apparently unaware of the impending visit.