Four Armenian servicemen were killed and three Azerbaijani soldiers wounded on Friday, the two countries said, as they accused each other of engaging in a new round of clashes.

Tensions between Baku and Yerevan have escalated sharply in recent months, as both sides accuse the other of cross-border attacks.

"As a result of an Azerbaijani provocation, four servicemen were killed and one wounded on the Armenian side," Armenia's defence ministry said, after earlier reporting two were killed.

The ministry said earlier that Azerbaijan had fired at Armenian positions near the town of Sotk, less than ten kilometres (six miles) from the Azeri border.

Azerbaijan said two of its soldiers were injured by an Armenian drone strike in the region of Kalbajar, on the other side of the border, while another was injured in cross-border fire.

"We declare that all responsibility for the tension and its consequences lies with the military-political leadership of Armenia," Baku's defence ministry said.

Both sides regularly blame each other for starting the violence and both sides accuse the other of spreading disinformation.

The latest clashes mark another blow to achieving peace between the two ex-Soviet republics, which have for decades been locked in a bitter dispute over the region of Nagorno-Karabakh.

Yerevan and Baku have fought two wars for control over the region, which is internationally recognised as part of Azerbaijan but largely populated by ethnic Armenians.

Armenia has accused Azerbaijan of blocking food and aid supplies to Armenian-populated towns in Nagorno-Karabakh via the Lachin corridor, the sole road linking Armenia to the region.

Yerevan and international aid groups have warned the humanitarian situation in the mountainous region is dire and deteriorating, with shortages of food and medicine.

The two sides have been unable to reach a lasting peace settlement despite mediation efforts by the European Union, United States and Russia.