Russia's defence minister told President Vladimir Putin on Monday that some of Moscow's massive military drills in Russia and Belarus were coming to a close. 

"Some of these drills are ending, some will be completed in the near future," Sergei Shoigu told Putin in a meeting. 

He added that some of the exercises, which began in December, were ongoing.  

Shoigu told Putin that "large-scale" exercises have taken place across Russia's western military districts and in almost all of its fleets -- "in the Barents Sea, the Black Sea, the Baltic Sea and with the Pacific Fleet".

Russia has massed around 100,000 troops near Ukraine's borders, with the US and its allies warning that Moscow could be planning an imminent invasion. 

The West has been particularly alarmed by Moscow's massive drills in Belarus, north of Ukraine. But Russia on Monday appeared to show signs of easing tensions.

Ahead of his meeting with Shoigu, Putin met with Foreign Minister Sergei Lavrov, who told him that a diplomatic solution with the West was still possible.

Shoigu also told Putin that Russia's Pacific Fleet had discovered what it believed to be a US submarine off its Far Eastern coast.

He called the incident, which the defence ministry reported on Sunday, "completely incomprehensible".