SOFIA - Bulgarian police have detained 47 illegal immigrants in the village of Herakovo, some 20 km northwest of the capital, the Ministry of Interior said in a statement on Tuesday.

The police operation was held on Monday after receiving information that “persons looking like immigrants” were in the yard of a house in the village, the statement said.

Four identified themselves as Pakistanis and the rest - as citizens of Afghanistan, it added. The investigation is ongoing. Bulgaria is located on a migrant route to Central and Western Europe. According to official data, the Ministry of Interior arrested 2,989 illegal immigrants in 2017.

Meanwhile, prosecutors said they have broken up a scam run by Bulgarian officials which had enabled thousands of foreigners to fraudulently obtain passports - and with them visa-free travel across the EU.

The scheme allegedly involved employees of the State Agency for Bulgarians Abroad, who are suspected of selling fake certificates of Bulgarian origin to people in neighbouring states.

Prosecutors said in a statement they had launched a probe into the work of the agency on several counts, including setting up an organised crime group, bribe taking, document forgery and abuse of office.

The prosecutor overseeing the inquiry, Angel Kanev, said no further details would be released at this stage.

However, local media cited prosecution sources as saying that the head of the agency, Petar Haralampiev, had been arrested in Monday’s operation, along with more than 20 other people - his subordinates and alleged intermediaries between the agency and those seeking Bulgarian passports.

The scheme is alleged to have catered to fraudulent applicants in non-EU members Ukraine, Moldova and Macedonia, all of which have significant minorities of ethnicBulgarians.

After Bulgaria joined the EU in 2007, there was a rush of passport applications from those countries by people who could prove they had at least one Bulgarian ancestor.

Under the scam, prosecutors say applicants paid up to 5,000 euros ($5,690) to obtain a fake certificate of Bulgarian origin.

Thousands of people reportedly took advantage of the scheme, with press reports claiming the agency was issuing around 30 fake certificates per week.

The agency chief is normally appointed by the government of the day.