TBILISI - U.S. House of Representatives Speaker Nancy Pelosi on Sunday strongly condemned what she said were "illegal" border attacks by Azerbaijan on Armenia, using a visit to the Russian military ally to pledge American support for Armenian sovereignty.

Speaking in Yerevan, Pelosi said her trip had particular importance following the "illegal and deadly attacks by Azerbaijan on Armenian territory" which led to border clashes in which more than 200 people were killed.

"We strongly condemn those attacks," Pelosi said. "This was initiated by the Azeris and there has to be recognition of that."

Pelosi said it was clear that the border fighting was triggered by Azeri assaults on Armenia and that the chronology of the conflict should be made clear.

The United States, Pelosi said, was listening to Armenia about what its defence needs were and said Washington wanted to help and support Armenia in what she cast as a global struggle between democracy and autocracy.

A senior Armenian official expressed unhappiness last week with the response of a Russian-led military alliance to Yerevan's request for help.

"We are very dissatisfied, of course. The expectations we had were not justified," parliamentary speaker Alen Simonyan told national television, likening the Collective Security Treaty Organisation to a pistol that did not shoot bullets, Interfax news agency reported.

Pelosi said it was interesting that Armenia was disappointed by the response from the Russian-led alliance.

(Writing by Guy Faulconbridge, Editing by William Maclean and Emelia Sithole-Matarise)