By Nailia Bagirova and Lucy Papachristou

BAKU (Reuters) -Azerbaijan demanded on Wednesday that Russia punish those responsible for the deaths of two Azerbaijani men in police custody, refusing to back down in a growing diplomatic dispute.

The South Caucasus country summoned the Russian ambassador in Baku to protest over the "illegal actions" of Russian police and accuse Moscow of undermining bilateral relations.

"It was reiterated that Azerbaijan expects a comprehensive and objective investigation from Russia into the violations committed by Russian law enforcement authorities and the punishment of those responsible," the Azerbaijani Foreign Ministry said.

Russia said certain forces, which it did not specify, were trying to wreck the relationship between the two neighbours, and urged Baku to repair it.

The diplomatic furore highlights a growing assertiveness toward Moscow on the part of Azerbaijan, an oil-producing former Soviet republic that has cultivated close ties with Turkey and has been boosted by military victories over longtime rival Armenia since 2020.

The dispute began when two ethnic Azerbaijani brothers died after being arrested last week during police raids as part of a murder investigation in the Russian city of Yekaterinburg.

Russian authorities have said one of the men died of heart failure, but have not said how the other died. Azerbaijan says the pair were tortured and beaten to death.

"It was emphasised that the explanation provided by the Russian side contradicts the clear signs of severe violence on the victims’ bodies and the forensic reports," its foreign ministry said.

Further fuelling the tensions, Azerbaijan this week arrested two Russian state journalists on fraud charges and about 15 other Russians on suspicion of drug trafficking and cybercrime.

AZERBAIJANI PUSHBACK

Zaur Shiriyev, non-resident scholar at the Carnegie Russia Eurasia Center, said Azerbaijan was pushing back against Russia's "former hegemonic influence in the region", which had faded after Russia became distracted by its war in Ukraine.

"At this point, Russia’s loss of dominance in the South Caucasus seems hard to reverse. It still has power, but no longer sets the tone," he said in emailed comments.

"Azerbaijan's more assertive actions are a response to this shift. And they don’t fit with the kind of one-sided, top-down relationship Moscow is used to, like the one it has with Belarus," Shiriyev said.

Azerbaijan's relations with Russia have been under strain since late last year, when 38 people were killed in the crash of an Azerbaijani airliner that Baku says was accidentally shot down by Russian air defences.

Nemat Avazov, the head of Baku's investigation into the accident, told reporters on Wednesday that his team would release its findings in the coming days.

Russian Foreign Ministry spokeswoman Maria Zakharova said Moscow had been cultivating ties with Baku for many years based on mutual respect, but unknown actors were now trying to use the situation to "warm up their hands" - a Russian phrase meaning to enrich oneself.

"Just don't let them get burned," she told Sputnik Radio in an interview. "Because for us, for the two peoples, friendship relations are extremely important. And those who want to spoil them should think carefully about what they are doing."

(Additional reporting by Dmitry Antonov in Moscow, writing by Mark Trevelyan and Lucy Papachristou; Editing by Andrew Osborn and Bill Berkrot)