Bulgarian Foreign Minister Daniel Mitov made clear on Wednesday the country leaves the door open for talks that could bring about a "balanced format of drills in the Black Sea".

Mitov told the Bulgarian National Television's morning program that NATO must show its determination to defend member states as there is "a buildup of armed forces in the Black Sea on behalf of Russia" and to react to imbalances created by the "annexation of Crimea".

The minister's appearance on BNT comes against the backdrop of tensions that surfaced last week over reports of a proposal by Romanian President Klaus Iohannis, who suggested Bulgaria should joint Romania and Turkey's effort to build a Black Sea fleet countering Russia.

While Borisov declared his staunch rejection of the idea, he voiced his suspicions that Mitov and Defense Minister Nikolay Nenchev (as the latter was meeting counterpart Mihnea Motoc) might have made arrangements behind his back.

But both Nenchev and President Rosen Plevneliev, who allegedly embraced the flotilla proposal, said the only option being discussed with NATO counterparts is the establishment of a multinational Romania-based brigade to which Bulgaria could send 400 troops.

Mitov stressed Bulgaria had not taken on any commitment to engage in a "regional format" as of the moment, adding there were no intentions among partners to "attack or fight a war against anyone".

In his words, there are a number of interpretations of the bast week's developments "bordering conspiracy theories".

Mitov also commented on the migrant readmission agreement signed with Turkey whose implementation was reportedly brought to a halt, with Borisov claiming Ankara had failed to fulfill all requests from Bulgaria to sent back migrants. The country's embassy denied the reports.

"[Turkey] says it ratified the agreement, but the Council of Ministers of Turkey has to adopt the way in which the agreement will be implemented technically," Mitov explained, adding the 195 refusals by Turkey to take in migrants that had crossed into Bulgaria was also a problem for other countries whose requests were not granted.

The readmission agreement, which Bulgaria signed as part of the EU-wide agreement with Turkey in a deal to curb the migrant flow into Europe, is one of the prerequisites for Ankara to have EU visas for its citizens lifted.