Documents Show Link Between AT&T and Agency** in Eavesdropping Case

** The 'Agency' is NSA.--Dictynna

By JOHN MARKOFF and SCOTT SHANE

SAN FRANCISCO, April 12 — Mark Klein was a veteran AT&T technician in 2002 when he began to see what he thought were suspicious connections between that telecommunications giant and the National Security Agency.

But he kept quiet about it until news broke late last year that President Bush had approved an N.S.A. program to eavesdrop without court warrants on Americans suspected of ties to Al Qaeda.

Now Mr. Klein and a few company documents he saved have emerged as key elements in a class-action lawsuit filed against AT&T on Jan. 31 by a civil liberties group, the Electronic Frontier Foundation. The suit accuses the company of helping the security agency invade its customers' privacy.