British Foreign Secretary Philip Hammond is expected in Sofia on Wednesday to discuss both bilateral and EU issues, with security also on the agenda.

Hammond comes at the invitation of his Bulgarian counterpart Daniel Mitov, but some British media outlets suggest he is to visit virtually every EU member state prior to this year's general election in the UK "to build support for major reform of Brussels," according to the Daily Mail.

The reason is that David Cameron, the UK's Prime Minister, reportedly instructed him to embark on the tour to ensure leaders' approval of British plans to renegotiate EU membership terms and secure a process of devolving some powers to national governments.

Cameron has also promised to hold an in/out referendum on Britain's EU membership if his party wins the election.

Net migration, allegedly boosted by Bulgarians and Romanians arriving in the UK after restrictions were lifted in 2014, have recently been a source of concern for his government, with London planning to restrict benefits and impose a time limit for jobless migrants to stay in the country in order to curb the influx of the EU.

Mitov for his part maintains employment among migrants from the EU, including those from Bulgaria and Romania, is generally higher than the UK's average level.

At the same time the situation in Europe in the light of developments in Ukraine, as well as joint effort to fight terrorism, will also be issues of discussion between the top diplomats. The latter is of particular interest following last week's events in Paris where a total of 17 people were killed in three days by Islamic extremists whose allegiance to a certain group is yet to be verified.

Hammond is also set to meet President Rosen Plevneliev and Prime Minister Boyko Borisov.

Wednesday's visit will be the first by a British Foreign Secretary in 16 years.

On Thursday, January 15, US Secretary of State John Kerry is also due in Bulgaria.