Antitrust regulators in the USA are not quite ready to give the green light to Teva Pharmaceutical Industries' proposed $6.8 billion acquisition of Cephalon.

Both of the companies has received a request for additional information, known as a 'second request', from the US Federal Trade Commission. They say they have been cooperating with the FTC staff since shortly after the announcement of the transaction last month.

Teva noted that the effect of the second request is to extend the waiting period for clearance of the buy until thirty days after the parties have "substantially complied with the request, unless that period is terminated sooner by the FTC". The companies added that they continue to expect that the deal will be completed in the third quarter of 2011, following approval from the FTC and its European counterpart, as well as the go-ahead from Cephalon stockholders.

Teva's bid for Cephalon beat a hostile offer made in April by Valeant Pharmaceuticals International which had been prepared to pay $5.7 billion. The deal will significantly boost the Israeli drugmaker's branded business.