RIM has come out fighting in its ongoing legal battles with NTP over the Blackberry.

The company has accused NTP of prolonging an investigation into the validity of its patents at the heart of the case in the hope of getting an injunction against RIM before they are struck down.

If the patent are valid, RIM is willing to settle the case and would agree to pay a fair royalty rate, RIM's CEO Jim Balsillie wrote in The Wall Street Journal yesterday.

Analysts had expected RIM to settle the patent dispute after a judge announced he would not wait for the decision by the US Patent and Trademark Office (PTO) before deciding whether to grant a US-wide injunction against the sale of the popular Blackberry wireless e-mail client.

The PTO has already issued "non-final office actions" that invalidate NTP's claims at issue in the dispute. NTP's patents cover a system for distributing wireless e-mail to mobile devices.

Last week, the PTO denied several NTP requests for more time to respond to the preliminary findings and created a special team to handle claims related to the case.

The patents were initially rejected because other inventions similar to the NTP patents were on record prior to NTP's filing, the PTO said in June. Since then, the PTO has also learned of additional prior art developed by Norwegian telco Telenor.

NTP has the right to appeal any final action to the PTO's board of appeals, and beyond that to the US Court of Appeals. The entire appeals process could still take years.

Earlier this year, NTP and RIM agreed to a settlement with a lump-sum payment of $450 million that did not involve royalties, but it later fell apart. The Wall Street Journal reported last week that NTP was now seeking 5.7 percent of RIM's revenue on BlackBerry sales.