Defence Secretary Gavin Williamson has denounced Russia's 'act of aggression' after RAF planes were forced to intercept the Kremlin's bombers, who were approaching UK airspace today.

RAF planes and French military aircraft scrambled to the North Sea today amid reports Russian planes were heading unannounced towards the UK.

Defence Secretary Gavin Williamson said: 'Russian bombers probing UK airspace is another reminder of the very serious military challenge that Russia poses us today.

'We will not hesitate to continually defend our skies from acts of aggression.

An RAF Typhoon fighter jet (bottom right of the image) has been circling above the North Sea amid reports a group of Russian aircraft (also pictured) were flying towards UK airspace

'Once again the rapid reactions of our RAF have demonstrated how vital our Armed Forces are in protecting Britain.'

Handout photographs show the RAF Typhoon fighter going out to intercept two Russian Long Range Blackjack bombers and escort them from British airspace.

An RAF Voyager refueling jet circled off the coast of Northumbria for more than three hours after taking off from Brize Norton airbase shortly before midday.

It is thought the plane was supporting RAF Typhoons from the Lossiemouth base. The Russian Long Range Blackjack bomber is seen with a red star adorned on its tail

It is thought the aircraft may have been supporting Typhoon fighter jets patrolling UK airspace, although the Ministry of Defence has declined to confirm this.

A security source told the Reuters news agency that a French fighter and support planes were also sent up to investigate 'suspected Russian fighter aircraft'.

Security sites in Moscow meanwhile reported two Russian planes flying towards Britain from the Barents Sea.

It is unclear why the Russian jet was approaching UK airspace, but it was eventually escorted out by the British jet

A flight pattern of the RAF refueling plane shows is circling over the North Sea. It is believed it was supporting Typhoon jets patrolling UK airspace

Earlier this month, British, French and German fighter jets simulated flight interceptions over Western Europe as part of NATO drills to deter Russian planes from entering allied airspace.

Fighter pilots carrying air-to-air missiles from 10 NATO nations took turns to simulate the interception of a potential enemy plane en route to Spain.

The team performed visual inspections of the aircraft's status by hovering off the wings at speeds of 560 mph.

Around 60 Nato jets, mainly from European allies, are currently on alert to defend alliance airspace, as NATO deals with a dramatic increase in Russian air activity on its borders since Moscow's annexation of Crimea in 2014.

In 2016, there was a record 870 interceptions in the Baltics alone.

Russia has cranked up the pressure this summer, holding the huge 'Vostok 2018' wargames in the country's eastern regions.

Nato will hold its biggest exercise since 2002 in October and November in Norway, called Trident Juncture, and involving non-NATO Finland and Sweden, with more than 40,000 troops.

RAF Typhoon fighter aircraft were scrambled from RAF Lossiemouth today to monitor two Russian planes approaching UK airspace, the Ministry of Defence has said.

The Russian Blackjacks long-range bombers were not talking to air traffic control, making them a hazard to all other aviation, the statement said.

Russian websites suggested military planes had taken off from bases near Moscow and headed up over the Arctic circle towards the UK

Russian websites claimed Tupolev Tu-160, so-called 'Blackjack bombers' were also in the air