In yet another move to stop Royal KPN’s unsolicited buyout offer, wholesale VoIP provider iBasis has brought a second suit against the Dutch telecommunications company.

The latest suit was filed in a New York U.S. District Court, bringing the battle to a federal level. The lawsuit alleges that KPN and certain members of its management have violated federal securities laws.

KPN was not immediately available for comment, but had called iBasis’ previous lawsuit filed in Delaware Chancery Court “entirely baseless.” KPN currently holds a 56 percent stake in iBasis, whose customers include KPN, KPN Mobile, Verizon, Vodafone, China Unicom, Skype and Telefonica.

In the federal suit, iBasis reiterated its previous allegations against Royal KPN, saying the telco’s bid of $1.55 per share in cash for the remaining shares of the company was “grossly inadequate.” It claims that KPN “disseminated false and misleading public filings that prevent iBasis’ stockholders from making an informed decision about whether to tender their shares.”

The lawsuit further claims that KPN’s offer was the result of a “fraudulent scheme” to drive down its stock price, buy shares from minority stakeholders and take the company private. Three of iBasis’ largest shareholders have already voiced support for the lawsuit, rejecting KPN’s tender offer.

KPN has said its offer price represents a 19 percent premium to the $1.30 closing price of the shares on July 10, the trading day before the offer was made.

Shares of iBasis fell by a penny to close at $2.17 on Tuesday. The stock, which traded at a 52-week high of $4.25 a year ago, bottomed at 51 cents in March and has been steadily regaining ground in the last few months.

Wireless Week Associate Editor Maisie Ramsay contributed to this report.