MOSCOW (Reuters) -Tensions between Russia and Azerbaijan rose on Monday after the Kremlin said it disagreed with a decision by Azerbaijan to cancel Russian cultural events in response to the arrest in Russia of ethnic Azerbaijanis suspected of serious crimes.Investigators in the Russian industrial city of Yekaterinburg conducted a slew of raids last week in connection with historic unsolved crimes, including serial killings. They said they had detained six people, all of whom had Russian passports, but they also said two suspects had died.One of the suspects died of heart failure, investigators said in a statement, and medical tests would reveal the cause of death of another suspect.AdvertisementAdvertisementAdvertisementAdvertisementBaku has accused the Russian police of carrying out extrajudicial killings "on ethnic grounds", an allegation Moscow has rejected.On Monday, police in Azerbaijan said they were carrying out raids at the office of Sputnik Azerbaijan, a local affiliate of Russian state media agency Rossiya Segodnya.Russia's charge d'affaires was previously summoned by the Foreign Ministry over what it called the "brutal killings", and Azerbaijan's parliament pulled out of planned bilateral talks in Moscow and cancelled a visit by a Russian deputy prime minister.On Sunday, Azerbaijan's cultural ministry said it was also cancelling cultural events planned by Russian state and private organisations due to "the demonstrative targeted and extrajudicial killings and acts of violence committed by Russian law enforcement agencies."AdvertisementAdvertisementAdvertisementAdvertisementAsked about the culture ministry's decision, Kremlin spokesman Dmitry Peskov said on Monday: "We sincerely regret such decisions. It is important to continue working to clarify the reasons and nature of the events that, in the opinion of the Azerbaijani side, caused such steps."We believe that everything that's happening (in Yekaterinburg) is related to the work of law enforcement agencies, and this cannot and should not be a reason for such a reaction," Peskov told reporters.(Reporting by Dmitry Antonov; Writing by Lucy PapachristouEditing by Andrew Osborn)