China said on Tuesday that it handed back an underwater research drone to the US after it seized it last week, an incident which added to simmering tensions between the world’s biggest militaries.

The handover comes after Chinese media lambasted Donald Trump for accusing China of theft – a charge which was also denied by officials in Beijing.

China’s Defence Ministry said on its website: “After friendly consultations between China and the US, the unmanned underwater vehicle has been transferred smoothly in relevant waters of the South China Sea at noon on December 20.”

The Pentagon said on Friday that a Chinese naval vessel, which had been shadowing the USNS Bowditch, "unlawfully" grabbed the unmanned underwater vehicle around 50 nautical miles northwest of Subic Bay in the Philippines.

Beijing, which initially accused the US of "hyping up" the drone incident, agreed to return it following negotiations.

US officials said on Monday that they expected the unmanned underwater vehicle (UUV) would be returned in the near future.

The seizure triggered a diplomatic protest from Washington and also prompted angry Tweets form Mr Trump, the president-elect.