Moscow/Yerevan (dpa) - One week after a ceasefire was agreed, the fighting in the disputed region of Nagorno-Karabakh has continued, with Azerbaijan on Saturday reporting heavy attacks overnight by the Armenian side on Ganja, the country's second largest city.

At least 13 people were killed in the rocket fire, the Civil Defence Ministry said in the capital Baku, adding that the bodies were found under the rubble of destroyed houses. In addition, there were more than 50 injured.

Images distributed by Azerbaijan showed rescue workers looking for survivors in destroyed houses. The authorities spoke of considerable damage.

The Azerbaijani Ministry of Defence said it had made further gains on the front line. According to President Ilham Aliyev, his military has also brought several villages and a city in the conflict area under Azerbaijani control.

Armenia in turn reported rocket attacks by the Azerbaijani side, including on the capital of Nagorno-Karabakh, Stepanakert, with at least three civilians injured there.

Both sides accused each other of violating the ceasefire, which was brokered the previous Saturday by Russia. However, the agreement was broken shortly after it came into force.

The two ex-Soviet republics have been fighting for decades for the mountainous region with around 145,000 inhabitants. Christian Nagorno-Karabakh is controlled by Armenia, but under international law it belongs to the Muslim nation of Azerbaijan.

In a war that followed the collapse of the Soviet Union some 30 years ago, Azerbaijan lost control of the area. A fragile ceasefire has been in place since 1994.