U.S. voice traffic carrier iBasis said some shareholders intended to reject Dutch telecoms group KPN's increased bid of $2.25 per share for the company.

The stockholders, the Trustee of the Singer Children's Management Trust and Millennium Management LLC, own about 4.2 percent and 3.6 percent respectively of iBasis's common stock, the company said in a statement on Friday.

Other large stockholders have also informed iBasis that they do not intend to tender into KPN's revised offer, iBasis said.

On Monday, KPN, which owns 56 percent of iBasis, raised its offer from $1.55 per share for the remaining stake after iBasis had rejected it as grossly inadequate and opportunistic.

(Reporting by Gilbert Kreijger; Editing by Dan Lalor)