Armenian military units continued to attack civilian areas in Azerbaijan’s Ganja, Barda, Beylagan and other cities with missiles and rockets, the aide of the Azerbaijani President Ilham Aliyev said Monday.

In a statement on Twitter, Hikmet Hajiyev called Armenia’s attacks "barbarism and vandalism."

"Sign of weakness and panic of Armenia’s political-military leadership," Hajiyev said.

Stepping up its bellicose rhetoric, the separatist leadership of Nagorno-Karabakh threatened to "expand subsequent (military) actions to the entire territory of Azerbaijan."

Separatist leader Arayik Harutyunyan warned that it would now consider "military facilities in Azerbaijan's big cities" as "legitimate targets."

"I call on the residents of these cities to immediately leave," Harutyunyan said in a post on Facebook.

On Sunday, Armenia also hit the Khizi-Absheron region near Azerbaijan’s capital Baku with midrange missiles.

Azerbaijan's second-biggest city, Ganja, came under heavy missile attacks by Armenian forces leading to the death of an Azerbaijani civilian while four others were wounded.

In statements posted on its website on Sunday, Azerbaijan's Defense Ministry said Ganja, a city in the country's west, and several other civilian areas were under fire from rockets and shelling.

"Indiscriminate missile attacks are launched against Ganja, Füzuli, Tartar and Jabrayil cities of Azerbaijan from the territory of Armenia. Ganja is the second biggest city of Azerbaijan. 500.000+ population," Hajiyev said in a tweet.

Armenia denied that it had directed fire "of any kind" toward Azerbaijan, but the Armenian separatist leader said his forces had destroyed a military air base in Ganja.

Arayik Harutyunyan said his forces would target Azerbaijani cities, adding: "Permanent military units located in the large cities of Azerbaijan from now on have become the targets of the defense army."

"Delivering fire on the territory of Azerbaijan from the territory of Armenia is clearly provocative and expands the zone of hostilities," Azerbaijani Defense Minister Zakir Hasanov said.

Meanwhile, Azerbaijan's armed forces liberated 22 settlements from the Armenian occupation amid ongoing border clashes in Nagorno-Karabakh, Turkey's Defense Ministry said Monday.

"According to information from reliable Azerbaijani sources, a total of 22 settlements have been liberated from occupation so far in the operation launched by Azerbaijani Armed Forces to reclaim occupied territories," the ministry said.

The military hung Azerbaijani flags in areas liberated from Armenian occupation, a statement by the Azerbaijani Defense Ministry said on Twitter.

The ministry shared a video showing Azerbaijani troops walking on the streets of Talish village, which had been occupied by Armenia since 1994.

In a TV address on Sunday, Aliyev said his country was determined to liberate Nagorno-Karabakh from Armenian occupation.

"Nagorno-Karabakh is Azerbaijani territory. We must return, and we will return," he said, adding that Azerbaijan had waited 30 years to recover its lands.

Aliyev urged Armenia to set a timetable for the withdrawal of its occupation forces, while he vowed to rebuild all of the cities that were liberated, including restoring all mosques that were damaged by Armenian forces.

Turkish officials have expressed solidarity with Azerbaijan, saying that they would provide necessary support if Baku asked for it.

As soon as the violations began, Ankara reiterated its support for Azerbaijan, with many officials, mainstream parties and the Turkish Foreign Ministry declaring unwavering backing of its brotherly Turkic nation.

However, although Turkey’s position is in line with international law, some countries tried to target Ankara for its support of Baku.

Border clashes broke out last week when Armenian forces targeted Azerbaijani civilian settlements and military positions, leading to casualties. Azerbaijan's parliament declared martial law in certain cities and regions following Armenia's border violations and attacks in Nagorno-Karabakh.

Relations between the two former Soviet nations have been tense since 1991 when the Armenian military occupied Nagorno-Karabakh.

Four U.N. Security Council (UNSC) and two U.N. General Assembly (UNGA) resolutions, as well as many international organizations, have demanded the withdrawal of the occupying forces.