The chief executive of German energy producer Uniper (UN01.DE) has criticized Finnish suitor Fortum (FORTUM.HE) for a lack of clarity about its intentions in a planned 8 billion euro ($9.6 billion) takeover of the company.

Fortum has agreed to buy 47 percent of Uniper from Uniper's parent E.ON (EONGn.DE) and offered the same price to the other shareholders, but it faces pressure to raise its offer from hedge funds Elliott and Knight Vinke, who have built up stakes.

Meanwhile, the Finnish utility is dragging its feet over job guarantee negotiations, Uniper Chief Executive Klaus Schaefer told the Rheinische Post newspaper in an interview published on Saturday.

 "Talks are not going as speedily as we would like," he said. "Fortum is still failing to provide clarity about its goals."

Just 0.17 percent of outstanding Uniper shares had been tendered to Fortum by Dec. 27, at the offer price of 22 euros per share. The shares closed at 26 euros on Dec. 29. The offer closes on Jan. 16.

Knight Vinke has 5 percent of Uniper and has said it will not tender its stake. Elliott, which has not said how it will respond, has 7.4 percent.