Sofia, September 3, 2015/ Independent Balkan News AgencyBy Clive Leviev-Sawyer of The Sofia GlobeBetween 130 and 160 people were detained in Sofia in an operation by police, the State Agency for National Security and the Interior Ministry's Migration Directorate against illegal migration.The operation took place on the night of September 2 in the region of the Women's Market in the centre of the Bulgarian capital city.Interior Ministry chief secretary Georgi Kostov said that the operation was based on information about people staying in the country illegally.People had been taken into custody after being unable to explain their legal status in the country.Kostov said that eight or nine of those detained had been released after it was established that they had legal refugee status.Those held would be accommodated in reception centres."Our colleagues from the Migration Directorate will accommodate them in reception centres, will talk to them, and establish how they entered the country, if they have to be granted refugee status, and the necessary administrative measures will be taken," Kostov told local television station bTV.He said that about 5000 people had been detained since the beginning of 2015 while attempting to enter the country at the Bulgarian-Turkish border illegally.A further about 5000 illegal migrants had been detained since the start of 2015 while leaving Bulgaria at the Bulgarian-Serbian border and in Bulgaria's interior.Kostov said that if people had come across the border from Greece, they could be returned to that country because Bulgaria had a readmission agreement with it. In the case of Turkey, this was not possible because there was no readmission agreement.He said that charges had been pressed against more than 200 Bulgarian citizens since the beginning of the year for involvement in people smuggling.Kostov said that the September 2 operation was part of continuing activity by the Interior Ministry and SANS. Since the beginning of the year, of the illegal migrants arrested, 4000 had been in Sofia.There have been periodic reports of such operations in Sofia, especially around the Women's Market area, where it has become customary for migrants to be accommodated in hostels and rooms in the neighbourhood.Bulgaria has been in headlines recently because a number of its nationals have been arrested in connection with the 71 people found dead in a lorry in Austria last week. Reports said that Austrian people were coming to Bulgaria on September 2 to continue their investigations.Border Police made several arrests in the previous weeks, after discovering migrants trying to illegaly get into the country from Bulgaria, in the seaside region at the Black Sea.