Latvia's president on Sunday said a Russian military drone had crashed on its territory, adding that airspace breaches had increased along NATO's eastern borders.

The Baltic state, which was once ruled by the Soviet Union but is now an EU and NATO member, has had tense relations with Moscow following independence, and ties have further deteriorated since Russia invaded Ukraine in February 2022.

A "Russian military drone... crashed in the eastern part of Latvia yesterday. There is an ongoing investigation," Latvian President Edgars Rinkevics said on X.

"We are in close contact with our allies. The number of such incidents is increasing along the eastern flank of NATO and we must address them collectively," he added.

Latvia's defence ministry said in a statement that the drone had flown into the country's airspace from Belarus and crashed in the municipality of Rezekne.

"This situation is a confirmation that we need to continue the work we have started to strengthen Latvia's eastern border, including the development of air defence capabilities and electronic warfare capabilities to limit the activities of UAVs of different applications," said Defence Minister Andris Spruds.

Fellow NATO member Romania also on Sunday said a Russian attack drone targeting civilian infrastructure in neighbouring Ukraine overnight had entered its airspace.

Bucharest strongly condemned the "renewed violation" brought on by Moscow's "illegal attacks".

Since launching its invasion, Russia has repeatedly carried out night attacks on cities across Ukraine, frequently targeting ports in the southern Odesa region after exiting a grain export deal.

Poland has also recorded at least two cases of its airspace being violated by Russian missiles or drones attacking Ukraine, most recently in December.

Warsaw late last month declared that a flying object had intruded into its airspace but later backtracked on the claim.

In an interview with the Financial Times published last week, Polish Foreign Minister Radoslaw Sikorski said Warsaw should have the right to shoot down Russian missiles targeting Ukraine before they enter Polish airspace, despite NATO opposition.