WASHINGTON - US Secretary of State Mike Pompeo on Friday held separate meetings with visiting foreign ministers of Armenia and Azerbaijan, the two countries in a conflict over the Nagorno-Karabakh region.

Pompeo emphasized the need to end the violence and protect civilians in his separate meetings with Armenian Foreign Minister Zohrab Mnatsakanyan and Azerbaijani Foreign Minister Jeyhun Bayramov, the State Department said in a short statement.

"The Secretary also stressed the importance of the sides entering substantive negotiations under the auspices of the OSCE Minsk Group Co-Chairs to resolve the conflict based on the Helsinki Final Act principles of the non-use or threat of force, territorial integrity, and the equal rights and self-determination of peoples," the statement added.

US National Security Adviser Robert O'Brien also met with Mnatsakanyan and Bayramov separately on the same day.

A new round of armed conflict broke out on Sept. 27 along the contact line of the Nagorno-Karabakh region. Armenia and Azerbaijan have been at loggerheads over the mountainous region since 1988. Peace talks have been held since 1994 when a cease-fire was reached, although there have been minor sporadic clashes since.