Four groups submitted financial and technical offers for a 518-million-euro project to extend a metro line in Thessaloniki, Greece’s second-largest city, Attiko Metro said on Monday.

A venture comprising AEGEK SA and Impregilo SpA, Seli SpA and Ansaldo STS SpA, and a group including TERNA SA, Alpine Bau GmbH and FCC Construccion SA submitted bids, the operator of the metro said in a statement on its website.

A third venture consisting of J&P-AVAX SA, Ghella SpA and France’s Alstom Transport SA also bid and Aktor SA made an offer on its own, according to the statement.

The winning offer to build five new stations and extend the metro line by almost 5 kilometers will be announced by the end of the year, Attiko Metro said.