Ukraine said Thursday it had sentenced a husband and wife to 15 years in prison for providing information to Russia that allowed its forces to launch a rocket strike at a hospital.

Prosecutors have opened thousands of cases into alleged collaboration with Moscow's forces since Russia invaded the country in February 2022.

The Security Services of Ukraine (SBU) also said Thursday it had detained a former soldier whom it accused of helping Russia plot strikes in the northeastern Kharkiv region.

The husband and wife -- sentenced on treason charges -- were accused of providing information on Ukrainian army positions, including "places of inpatient treatment for wounded Ukrainian soldiers," the SBU said in a statement.

"It was at their direction that the occupiers shelled a local hospital," in the southern city of Kherson, it said.

They were allegedly recruited by Russia's FSB security service after responding to an advert in a Russian Telegram channel offering payments in exchange for intelligence on Ukrainian positions.

Russian forces shelled a number of medical facilities in Kherson after Ukraine retook control of the southern city in November 2022.

The SBU also said Thursday it had detained a former serviceman accused of helping Russian forces "coordinate" attacks on the northeastern Kharkiv region.

It said the suspect, who faces up to eight years in prison, had tried to flee to Russian-held territory.

"He was encouraged to take these steps by his parents, who live in occupied territory," a statement read.

Ukrainian forces also said they had repelled a Russian sabotage group in the northeastern Sumy region.

The Russian forces were pushed back with artillery and mortar fire, it added.

Moscow's troops entered the Sumy region after the Kremlin launched the invasion of Ukraine in February 2022, but were pushed back by Ukrainian forces.