Mustafa Nayyem told RFE/RL on May 1 that it took hours before he was allowed to leave the airport after his arrival on April 30.

Nayyem was using a regular passport and not a diplomatic one because he had been invited to attend a conference in Armenia as a private person.

"The customs officers told me that they could not let me enter the country because I was on a list of individuals whose presence in Armenia was undesirable," Nayyem said.

After long additional checks, the Armenian border guards told Nayyem that he had been barred from entering Armenia at the request of "a third country."

"They politely asked me if I had any idea what country was interested in my not visiting Armenia and I answered no," Nayyem said.

"After the [Ukrainian] consulate and the organizers of the conference intervened, I was finally allowed to enter Armenia for once."

Nayyem said he was later told by Armenian politicians and Ukrainian Embassy officials that Russia and Armenia are in coordination regarding Ukrainian citizens who are on Moscow's sanctions list.

He said some other Ukrainian lawmakers and officials had found themselves in similar situations in the past.

"Armenia's sovereignty is being questioned here, especially if we take into account that Russia's sanctions list is a politically motivated document," Nayyem said.

Ties between Moscow and Kyiv have deteriorated drastically since Russia's seizure of Ukraine's Crimean peninsula in 2014 and its support for separatists in eastern Ukraine.

Russia, which is itself subjected to Western and Ukrainian sanctions, has also imposed punitive measures on hundreds of Ukrainian individuals and companies.