BEIJING (AP) — China has threatened to disbar as many as 20 lawyers known for taking sensitive human rights cases, several of the lawyers said Wednesday, in the latest apparent clampdown on legal activists.

Lawyers said officials with justice agencies had issued warnings to leading members of their law firms in meetings and over the phone and that annual accreditations have yet to be issued only days before the June 1 renewal date.

If carried through, the disbarments on technicalities would mark the broadest effort in recent years by the authoritarian government to rein in a growing number of activist lawyers. Previously, only a few were disbarred, though threats, beatings and other acts of intimidation have been common.

"Before they used to pressure individuals but now they have turned to this more systematic method," said Tang Jitian, whose employer, the Anhui Law Firm in Beijing, was among those warned. "The justice departments say the lawyers who defend human rights are inharmonious or unstable elements, but I think they are the ones who are unstable."

The campaign is having a "chilling effect on the legal profession" in China, New York-based Human Rights Watch said in a statement Wednesday.

Human Rights Watch and several lawyers said they believed the stepped-up pressure was linked to official anxiety about potential social unrest this year because it marks the 20th anniversary of the 1989 pro-democracy movement.

The lawyers now under threat include one who is defending a noted Tibetan Buddhist monk and others who have defended practitioners of the banned Falun Gong spiritual movement, or helped parents of children who died in last year's devastating earthquake in Sichuan province.

The Justice Bureau did not immediately respond to a faxed request for information Wednesday about accreditation delays and allegations of intimidation.

Because the warnings coincide with the license renewal period for both law firms and lawyers, they have added weight.

Lawyers said the implicit message was that firms should sabotage the renewal applications of their "problem lawyers," or risk having their firm's license or the licenses of other employees rejected. The easiest ways for a firm to lose an employee are to submit incomplete accreditation paperwork, an unfavorable review of their performance, or to simply not submit an application, they said.

Tang, who has defended farmers against rural land grabs and challenged police detention without trial, said if his license is not renewed by Sunday, he will be barred from working.

At least 20 other lawyers working for nine firms have reported the same delays in getting their license renewed, Tang and other lawyers said.

Jiang Tianyong, a lawyer with Beijing's Gaobo Longhua Law Firm, said his application was still pending as well. A former middle school teacher, he said the stalling was at least meant as a warning but if he is in fact rejected, he will appeal.

"They are using us as examples to scare the other lawyers into line," said Jiang, who recently defended a Tibetan Buddhist cleric against charges of concealing weapons in an area of China where anti-government protests occurred. Investigators said they found a pistol under a bed in his living room.

In the northeastern city of Harbin, Wei Liangyue said he was forced to give up his position as director of Jiaodian, a law firm he helped set up seven years ago, because he recently defended a Falun Gong practitioner. Had he remained in the position, he said, all 11 lawyers would have been disbarred.

Instead Wei appointed another partner to his former post and he became the only one to lose his license. He is still on staff at the firm but cannot practice law.