Sofia and Washington are ready to place an emphasis on economic ties, energy security, rule of law and security in bilateral ties, Bulgarian President Rosen Plevneliev and US Secretary of State John Kerry have said in a statement.

Judicial reform was also among the topics discussed, with President Plevneliev pledging 2015 would bring about changes toward that goal.

Kerry reiterated US President Obama's position that it Washington is firmly standing behind its NATO counterparts in the light of the crisis in Eastern Ukraine.

The US diplomat also praised Bulgaria's contribution to peacekeeping and humanitarian missions in Iraq and Afghanistan and also to building up defense potential of NATO in the Black Sea.

Plevneliev and Kerry's joint statement followed their talks held on Thursday at the Presidency in downtown Sofia.

In the 50-minute meeting, the two discussed various issues including trade, energy and security. The head of state pointed to Bulgaria's commitments to boost defense expenditure and modernize its army under NATO agreements, various media outlets report him as saying.

Plevneliev is a backer of continued dialogue on a EU-US free-trade deal (TTIP).

John Kerry is on a visit to Sofia on Thursday along with his deputy on European and Eurasian affairs, Victoria Nuland.

The two US diplomats are set to meet with Bulgarian Prime Minister Boyko Borisov and Foreign Minister Daniel Mitov.

Authorities have beefed up security throughout the capital's central area in the eve of Kerry's visit.