The Biggest opposition party in Bulgaria, BSP, has called for a parliamentary hearing of Prime Minister Boyko Borisov and the ministers of foreign affairs and defense over Romania's proposal to set up a "Black Sea fleet" countering Russia's influence in the region.

The idea was reportedly brought up in a meeting of Romanian President Klaus Iohannis with Bulgarian politicians. The former denied having used the word "fleet" and suggested there had been a problem with the translation, but mass circulation daily 24 Chasa wrote the issue had already been tabled by the country's Prime Minister, Dacian Ciolos.

Borisov later made clear Bulgaria would not engage in the setting up of a joint naval force in the Black Sea. After a meeting with his Romanian counterpart, Defense Minister Nikolay Nenchev said the only possibility that had been discussed was for Bulgaria to send troops for training in a future Romania-based NATO brigade.

However, the Bulgarian Socialist Party (BSP) argued on Wednesday the initiative was evolving "into some kind of a formal structure that is likely to be proposed and respectively approved at the [NATO Warsaw Summit]."

"It has become clear that talks have been held not only over the past month, but at least for six months [and] that the initiative is not only reduced to an increased number of joint exercises," the Bulgarian National Radio quotes socialist MP Angel Naydenov as saying.

Nenchev, alongside Foreign Minister Daniel Mitov, should also attend the hearing to explain the case to lawmakers, Naydenov added.

Mitov himself stressed in an interview with the Bulgarian National Television that Sofia had taken on no commitments to participate in an establishment of a joint naval force in the Black Sea.

Parliament Speaker Tsetska Tsacheva later replied Borisov would be unable to attend such a hearing before Friday.