Fighting between Azerbaijan and Armenian forces over the occupied Karabakh region continued until the fourth day.

Azerbaijan has vowed to pursue military action against Armenian troops in occupied Karabakh until a full Armenian withdrawal from the territory.

Armenian and Azerbaijani forces are engaged in the heaviest fighting in years over Karabakh, occupied by Armenians since in the 1990s during the collapse of the Soviet Union.

Border clashes broke out in occupied Karabakh, also known as Nagorno-Karabakh on early Sunday when Armenian forces targeted Azerbaijani civilian settlements and military positions, leading to multiple casualties. Armenia denies starting the fighting.

"We only have one condition: Armenian armed forces must unconditionally, fully, and immediately leave our lands," Azerbaijani President Ilham Aliyev said in televised remarks on Wednesday, the fourth day of clashes.

If "the Armenian government fulfils the demand, fighting and bloodshed will end, and peace will be established in the region," he added.

Earlier Wednesday, Azerbaijan's foreign ministry said in a statement that Baku was "resolutely determined to continue the counteroffensive operation until its sovereignty and territorial integrity is fully restored... (and) we clearly see the Armenian troops leaving the territory of Azerbaijan".

On Wednesday, Armenia and Azerbaijan rejected international calls for a halt to fighting and negotiations.

Nearly 100 people are confirmed to have died in the flare-up and both sides are claiming to have inflicted heavy losses on opposing forces.

International pressure for a ceasefire has mounted as fears grow that the conflict could escalate into all-out war.

The war between Azerbaijan and Armenia over Nagorno-Karabakh in the 1990s claimed 30,000 lives and the region it is still not recognised as independent by any country, including Armenia.

The UN refers to occupied Karabakh as a part of Azerbaijan in several non-binding Resulotions.

( Azerbaijan defending its land )
Turkey's Defence Minister Hulusi Akar and UK Defence Minister Ben Wallace discussed Armenian aggression towards Azerbaijan and attacks targeting civilians.