Bulgaria's defence ministry said on Tuesday that it has signed a 4.7 million euro ($5.4 million) deal with Russian Aircraft Corporation MiG for the overhaul of the country's three MiG-29UB trainer jets, as part of a framework agreement concluded last year. This is the second contract under the framework agreement, the ministry said in a notice. In March last year, the defence ministry signed a four-year framework agreement for the maintenance of MiG-29 fighter jets worth up to 21 million euro with Russian Aircraft Corporation MiG. The agreement envisages integrated logistics support of 15 fighter jets of the Bulgarian Air Force - 12 MiG-29A and three MiG-29UB - for a total of 1,450 flight hours per year. Bulgaria will get a 2% discount on contracts worth between 5 million euro and 10 million euro, 2.5% on contracts worth between 10 million euro and 15 million euro, and 2.8% on contracts worth over 15 million euro, the ministry said at the time. Bulgaria's government is expected to shortly start talks with the U.S. for acquisition of new F-16 fighter jets to replace its ageing fleet of MiG-29s .