BAKU: Postmortems on two Azerbaijani brothers who died in Russian police custody have shown that they were beaten to death, authorities in the South Caucasus country said on Tuesday as tensions rose sharply between Moscow and Baku.

Azerbaijani prosecutors said they had opened a criminal investigation into the alleged murders of Huseyn and Ziyaddin Safarov following their arrest last week in the Russian city of Yekaterinburg.

The case concerns `the torture and deliberate killing with particular cruelty of Azerbaijani citizens and ethnic Azerbaijanis by officers of law enforcement agencies of the Russian Federation`, the state prosecutor`s office said.

In a further deepening of the crisis, Azerbaijan on Monday detained seven Russian journalists, drawing a protest from Moscow. A Baku court placed two of them, Igor Kartavykh and Yevgeny Belousov, under formal pre-trial arrest on Tuesday on charges of fraud, illegal entrepreneurship and money laundering.

Kremlin spokesman Dmitry Peskov said the journalists` arrests were an `extremely emotional reaction` by Azerbaijan, and Russia aimed to negotiate their release.

An Azerbaijani government source said that about 15 more Russians had been arrested separately on suspicion of drug trafficking and cybercrime. The source shared videos showing them being handcuffed, made to march in line and bundled into police vans.

The cases threaten to severely damage relations between Russia and Azerbaijan, an oil-producing country and former Soviet republic that has close ties with Turkiye.-Reuters