Niger and Mali are both run by military governments that took power in recent coups and have turned to Russia and its Wagner mercenary group for support.

"It's a pity that Niger's authorities have decided to sever diplomatic relations with Ukraine without conducting any investigations into the incident in Mali and without providing any evidence regarding the reasons for such a step," the Ukrainian foreign ministry said.

Mali said Kyiv supplied intelligence to rebel troops, who then reportedly used it to kill dozens of mercenaries from Russia's Wagner paramilitary group and Malian soldiers in a battle last month.

It had pointed to a cryptic statement by a spokesman for Ukraine's military intelligence division, which it said amounted to an admission of Kyiv's involvement.

Andriy Yusov, a spokesman for Ukraine's GUR military intelligence unit, was quoted by state media as saying: "The rebels received all the necessary information they needed," without elaborating.

Malian government spokesman Colonel Abdoulaye Maiga said the government had been shocked to learn of the remarks.

Russia accused Kyiv of opening a "second front" in Africa.

The Ukrainian foreign ministry on Thursday repeated its rejection of the claims.

"The accusations against Ukraine... do not stand up to any criticism. They are groundless and untrue," it said.