"Some members of Congress are urging the popular website Twitter to stop hosting pro-Taliban tweets that celebrate attacks against American and allied forces in Afghanistan," the Los Angeles Times reported.

Twitter feeds, apparently from the Taliban, first appeared last year in Arabic and Pashto. An English-language feed started in April. Many of the posts refer to US troops in inflammatory terms.

"Mujahideen fighter kill 4 American cowards, hurts several more in encounter: GHAZNI," read one. "US terrorists martyr 12-year-old boy, detains many others: PAKTIKA," read another.

Twitter officials did not respond to requests for comment, the report said. But Twitter executives have told lawmakers that the micro-posts do not violate the website's terms of service because the Taliban is not listed by the State Department as a foreign terrorist organisation (FTO).

The move against the pro-Taliban Twitter feeds is part of a larger effort by Senator Joe Lieberman, chairman of the Senate homeland security committee, to persuade Internet companies to remove offensive videos and blog posts that promote terrorism.

Pressure also is coming from the NATO-led International Security Assistance Force in Kabul. This year, the ISAF began battling the pro-Taliban messages with tweets that countered insurgent claims. As a result, the two sides sometimes exchange a dozen tweets a day, the report said.

Lieberman has pressured other US websites to keep out content that he says could inspire terrorist acts. In a letter to Google Chief Executive Larry Page, he has complained that the company is failing to keep extremist videos and blogs off its servers.

Google has restrictions on posting pro-militant videos on its YouTube site, but Lieberman said those restrictions do not apply to its Blogger blogging site.

Lieberman pointed out that Jose Pimentel, who was arrested in New York on Saturday for allegedly planning terror attacks, published a website with links to bomb-making instructions and "hate-filled writings" using Blogger.

"Google's inconsistent standards are adversely affecting our ability to counter violent Islamist extremism online," Lieberman wrote.

A Google representative said the company does not allow content on Blogger that encourages other people to take violent action. Pimentel's Blogger website was disabled after his arrest.