Turkey's presidential spokesman on Wednesday scolded US presidential candidate Joe Biden for failing to urge Armenia to end its occupation of Azerbaijani land, Yeni Safak reports.

“Would you ask Armenia to end the occupation too?” Ibrahim Kalin wrote on Twitter, adding: “Or would you simply cave in to the smear campaigns of the Armenian lobby?”

Following weekend Armenian attacks based in Upper Karabakh, or Nagorno-Karabakh – an internationally recognized Azerbaijani territory occupied by Armenia – Biden wrote on Twitter Tuesday: “With casualties rapidly mounting in and around Nagorno-Karabakh, the Trump Administration needs to call the leaders of Armenia and Azerbaijan immediately to de-escalate the situation.”

He added: “It must also demand others – like Turkey – stay out of this conflict.”

Biden – the Democratic front-runner for the US presidency – also shared a Reuters story with the headline, “Turkey's Erdogan says Armenia must withdraw from Azeri lands,” referring to Turkish President Recep Tayyip Erdogan.

Since Armenia’s attacks last Sunday, tensions have continued to escalate, with Turkey firmly standing with Azerbaijan.

The EU, Russia, and NATO, among others, have urged an immediate halt to clashes along the frontier.

Relations between the two former Soviet republics have been tense since 1991, when the Armenian military occupied Upper Karabakh, or Nagorno-Karabakh, an internationally recognized territory of Azerbaijan.

Four UN Security Council and two UN General Assembly resolutions, as well as many international organizations, demand the withdrawal of the occupying forces.

The OSCE Minsk Group – co-chaired by France, Russia, and the US – was formed in 1992 to find a peaceful solution to the conflict, but to no avail. A cease-fire, however, was agreed on in 1994.