Armenia's prime minister Nikol Pashinyan told U.S. President Joe Biden in a letter on Saturday that recognition of the genocide is a matter of security to Armenia after a war in Nagorno-Karabakh last year.

Biden said on Saturday that the 1915 massacres and forced deportation of Armenians in the Ottoman Empire constituted genocide.

"The recognition of the genocide is a matter of truth, historical justice and security to the Republic of Armenia, especially in the light of the events that took place in our region last year," Pashinyan said in a letter to Biden published on his website.

A six-week conflict between Azeri and ethnic Armenian forces over in Nagorno-Karabakh and its surrounding areas was halted by a Russia-brokered deal in November, locking in territorial gains for Azerbaijan, backed by its close ally Turkey.

Baku said Biden's statement was "misrepresenting the events that happened 100 years ago".

"The falsification of history, attempts to "rewrite history" and its use for political pressure are unacceptable," said Azerbaijan's foreign ministry in a statement on Saturday.