The foreign ministry in Sofia has advised Bulgarian citizens travelling to Ukraine to avoid sites of public gatherings in view of “heightened public tensions” and protests in major Ukrainian cities.

The ministry on Wednesday recommended to Bulgarian citizens visiting Ukraine to carry always their passports with them and by no means leave unattended their belongings and documents.

Those travelling by car are advised to stop for a rest only in well lit places and leave no attractive or expensive items unattended in the cabin of the car.

Bulgarian citizens are also advised to register on the website of the foreign ministry or the Bulgarian diplomatic missions, indicating the place and period of their stay and leaving a contact number.

Ukraine said earlier this month it suspected that Russia planned an invasion after Moscow increased its military presence on the common border. The war of words between Russia and Ukraine has intensified following last week’s accusation that Kiev plotted a sabotage attack in Crimea, the BBC recalls.

Ukraine military was put on high alert with the country’s President Petro Poroshenko saying the Russian accusation of a sabotage action by Ukrainian special forces was false and aimed to justify future attacks by the Russian military.

The Russian Navy announced exercises in the Black Sea on August 12, a day after Russian President Vladimir Putin accused Ukraine of trying to provoke a conflict over Crimea.