German construction group Hochtief said Monday it plans to tighten its grip on Australia's biggest building company by raising its stake to 74 percent. Hochtief said in a statement it would offer to buy three out of every eight shares currently held by Leighteon shareholders for 22.15 Australian dollars apiece. That represented a total purchase price of 1.155 billion Australian dollars or 755 million euros ($1.05 billion) and would increase Hochtief's stake to 74.23 percent from 58.77 percent at present. The offer is still subject to regulatory approvals and will be funded from cash reserves and credit facilities, Hochtief said. The German group said it would also increase its representation on Leighton's board of directors to reflect the bigger shareholding. Hochtief is controlled by Spanish group ACS.