FRANKFURT - Construction group Zech is seen as the front runner to buy the German unit of bankrupt Dutch engineering services company Imtech, two people familiar with the deal said. A decision on Zech’s offer, which was discussed among creditors on Monday, is expected by the end of the week, they said, adding that other bidders remain in the race. Zech and administrator Peter Borchardt declined to comment. Imtech Germany filed for insolvency on Aug. 6, and the parent company followed suit a week later, capping a long slide that began in 2013 after accounting irregularities were uncovered at its Polish and German operations. Imtech Germany accounted for about a fifth, or 860 million euros ($964 million), of Imtech’s sales. Zech plans to keep about 75 percent of Imtech Germany’s staff and to continue ongoing projects such as work at Berlin’s new international airport. ($1 = 0.8923 euros)