Russia is believed to have jammed the satellite signal on an aircraft used by defense minister Grant Shapps to travel from Poland back to Britain, a government source and journalists travelling with him said Thursday.

According to a government source and journalists, the GPS signal was interfered with for about 30 minutes while the plane flew close to Russia's Baltic exclave of Kaliningrad.

Mobile phones could no longer connect to the internet and the aircraft was forced to use alternative methods to determine its location, they said.

The Russian defense ministry did not respond to a request for comment.

Prime Minister Rishi Sunak's spokesperson confirmed the incident had happened on Wednesday but added it was "not unusual."

"While travelling back from Poland yesterday, the plane carrying the Defense Secretary and his delegation temporarily experienced GPS jamming when they flew close to Kaliningrad," the spokesperson said.

"It didn't threaten the safety of the aircraft and it is not unusual for aircraft to experience GPS jamming near Kaliningrad, which is of course Russian territory."