(Reuters) -The Slovak government has asked police to investigate the former cabinet and defence minister Jaroslav Nad for donating fighter jets and an air defence system to Ukraine to help it defend against Russia's invasion, a government official said on Friday.

The new government under Prime Minister Robert Fico made a sharp policy turn after it took power in October 2023 and halted military supplies to Ukraine, although it has allowed commercial supplies to continue.

The previous Slovak government last year donated a dozen Russian-made MiG-29 fighters that Slovakia had grounded and most of which were not operational, as well as the KUB air defence system.

Donating the air defence system exposed Slovak airspace and endangered citizens, said Ìgor Melicher, state secretary at the Defence Ministry and a member of the ruling Smer-SD party.

"I am convinced that Nad betrayed Slovakia," Melicher told a briefing shown live on Facebook.

"The defence ministry is filing a criminal complaint for the suspicion of committing the crime of sabotage, or treason, abuse of power and failing fiduciary duties."

Nad has rejected any wrongdoing and said he would make the same decision again. There was no immediate fresh comment from Nad on Friday.

Former Ukrainian Defence Minister Oleksiy Reznikov told Reuters that Nad had been "proactive and professional" during his time in office.

"I can confidently state that Jaroslav's every action was directed at making sure that Slovak homes stayed safe, and that they never experienced what Ukrainians are currently living through," he said.

One of the arguments Melicher used is that the government had ruled whilst in a caretaker capacity and thus had limited authority to make foreign policy decisions.

The allegations are a symptom of the highly polarised Slovak political scene, where Fico has repeatedly accused his predecessors of pursuing criminal prosecutions against his party when he was in opposition.

His cabinet has scrapped a special prosecution unit that had gone after corruption, replaced key police personnel, and taken steps to replace management of public media.

The country is due to receive F-16 fighters ordered earlier to replace the MiGs.

(Reporting by Jan Lopatka in Prague, additional reporting by Thomas Balmforth in Kyiv; Editing by Sharon Singleton and Alistair Bell)