WASHINGTON, April 20: The directive by the US Immigration and Naturalization Service prohibiting disclosure of the names of post-Sept 11 detainees by states may make the task of keeping track of the arrested persons even more difficult for their countries’ missions here.

The missions already had to exert themselves to locate nationals rounded up by the US authorities following the Sept 11 attacks, and access to information about such persons might become harder to get in the wake of the new directive.

The directive, issued on Thursday, prohibits state and local governments from releasing the names of detainees. It has followed court rulings from federal judges ordering that documents and hearings in the case of a Lebanese activist must be made accessible to the public. The government accuses the Lebanese of links with alleged terrorist groups abroad and wants him deported.

In this particular case, the justice department, in response to the court orders, has agreed to release immigration documents, but newspaper reports say the justice department views this as a “narrow response” to an individual case, and officials have asserted they will continue to withhold information about other detainees.

Nearly 300 Pakistanis were arrested in the crackdown that followed the Sept 11 attacks. All of them except for 30 or so have since been deported. But somewhere around 50 other Pakistani nationals were held in a second wave of arrests that was aimed at detecting immigrants who had been ordered to be deported but had absconded. Of the 50, several had tried in the intervening period to legalize their status; some had got green cards and some had married American women in a bid to be naturalized. Most such cases date from 1995.