HOUSTON, Feb. 4 — Former Enron Corp. Chairman Kenneth L. Lay late Monday resigned from the board of directors, effectively severing all formal ties with the Houston energy company he helped build.

Lay was supposed to testify before the US Senate Commerce Science and Transportation Committee earlier in the day about Enron’s financial collapse. He notified the committee late Sunday that he would not appear citing a “prosecutorial” attitude of some members of Congress. The committee Tuesday will consider issuing a subpoena to force Lay to appear.

Lay said he resigned from the board because of multiple inquiries and investigations, “some of which are focused on me personally,” that had become a distraction from efforts to ensure Enron emerges from bankruptcy protection.

“My concern is for current and former Enron employees and other stakeholders, and I feel it is in their best interest for me to step down from the board,” he said. Lay served as CEO, chairman and board member of Enron Corp. since 1986.

He retired as CEO in February 2001, but resumed the role upon Jeff Skilling’s resignation in August 2001. Lay resigned as chairman and CEO of Enron on Jan. 23, as financial and political scandal enveloped the company.

Over the weekend, the Enron board of directors released a report which claimed company executives reaped millions of dollars from off-balance-sheet partnerships. The report said Lay personally approved some of the partnerships and criticized him for acting more as a director than manager.

Enron set up hundreds of partnerships to move debt off the balance sheet. The partnerships are legal if they are structured according to established accounting rules.