BBC News
Heavy fighting has erupted between Armenia and Azerbaijan over the disputed Nagorno-Karabakh region, with both civilians and combatants killed.
Accusing Azerbaijan of air and artillery attacks, Armenia reported downing helicopters and destroying tanks, and declared martial law.
Azerbaijan said it had begun a counter-offensive in response to shelling.
The region is internationally recognised as part of Azerbaijan but controlled by ethnic Armenians.
They broke away in the dying years of the Soviet Union. Both Armenia and Azerbaijan were part of the communist state, which sought to suppress ethnic and religious differences.
Amid the clashes, Azerbaijani President Ilham Aliyev said he was confident of regaining control over the breakaway region.
Martial law has also been declared in some regions of Azerbaijan.
Nagorno-Karabakh, also known as Artsakh, is a landlocked region in the South Caucasus, within the mountainous range of Karabakh, lying between Lower Karabakh and Zangezur, and covering the southeastern range of the Lesser Caucasus mountains.
The major cities of the region are Stepanakert, which serves as the capital of the Nagorno-Karabakh Republic, and Shusha, which lies partially in ruins.
Petroleum industry in Azerbaijan
The petroleum industry in Azerbaijan produced about 873,260 barrels (138,837 m3) of oil per day and 29 billion cubic meters of gas per year as of 2013. Azerbaijan is one of the birthplaces of the oil industry. Its history is linked to the fortunes of petroleum. It is poised to become an important oil and gas producer once again.
In April 2020, amid the Covid-19 pandemic, Baku supported anagreement between the Organization of the Petroleum Exporting Countries (OPEC) and other non-OPEC oil-producing countries to cut production in an effort to stabilise the oil market. Under the new agreement Azerbaijan would be expected to reduce its output by 164,000 barrels per day for the next two months. During this period, Azerbaijan would keep average daily crude oil production at a level not exceeding 554,000 barrels and the country would have to maintain daily oil production at the level of 587,000 barrels during the July-December period and 620,000 barrels between January 2021 and April 2022