Dutch telecoms group KPN agreed improved terms for the takeover of iBasis, securing the control it needs to turn around the loss-making global top-three voice traffic carrier.

KPN set its final offer for the 44 percent of iBasis shares it did not hold at $3.00 per share in cash, up from the $2.25 offered last month.

The companies said a special committee of iBasis's board unanimously approved the agreement and recommended stockholders to tender their shares.

U.S. carrier iBasis is at the heart of KPN's business unit, which is feeling the impact of the recession and is not showing any signs of recovery, KPN said last month.

iBasis, which provides international long distance telephone calls and provides retail prepaid calling services to mobile operators, said it carried about 24 billion minutes of international voice traffic in 2008.

Its customers include KPN, Verizon, Vodafone, China Mobile and Telefonica. KPN is taking full control of iBasis as it believes it can manage the company better when it has full control.

KPN became a 56 percent shareholder in October 2007 after it sold its global carrier services to iBasis.

The new offer implies an almost 131 percent premium over the closing price of iBasis shares on July 10, which was the last trading day before the announcement of KPN's tender offer.

In October, KPN raised its offer to $2.25 per share from an initial offer of $1.55.

Since then, the price of the offer has been at the centre of the dispute as iBasis accused KPN of concealing internal projections suggesting the company might perform better than projected.

(Reporting by Harro ten Wolde; editing by Simon Jessop and David Cowell)