Concord, N.H. ? Tyco International Ltd. plans to close 24 factories and eliminate 7,100 jobs, primarily in its electronics and telecommunications businesses.

The manufacturing and services conglomerate said Thursday it would hold on to its plastics division, which had been up for sale, and said it would spin off its CIT financial division. It also said it was scrapping a plan, announced in January, to break the company into four parts.

Tyco shares tumbled 19.9 percent, or $5.15 a share, to $20.75 in trading Thursday on the New York Stock Exchange.

The company’s stock had already been troubled in recent months by worries about the company’s accounting practices and debt load following Enron Corp.’s collapse.

Tyco did not release details about where or when the job cuts will take place. They represent about 3 percent of the company’s worldwide work force of almost 250,000 people. It said the charges resulted from a “fierce decline” in the electronics and telecommunications markets.

The announcements came as Tyco said it lost $1.9 billion, or 96 cents per share, in the three months ended March 31 in contrast to a profit of $1.1 billion, or 62 cents per share, a year ago. Revenue slipped to $8.66 billion from $8.81 billion a year ago.

Excluding the charges, Tyco’s earnings were 65 cents per share, 3 cents ahead of Wall Street expectations.

Tyco is a Bermuda-based company with headquarters in Exeter. Its products include electronic equipment, fire and security systems and disposable medical supplies.

In a letter to shareholders, chairman and chief executive Dennis Kozlowski said the company was still in negotiations to sell CIT but decided that spinning it off in a public offering would reduce Tyco’s vulnerability to debt markets, make the company less complex and allow it to focus on its core markets.

Kozlowski also said senior corporate managers would not receive bonuses this year.

The decision to stop the planned breakup was difficult, Kozlowski said.

“In retrospect, it is now clear that we took the market by surprise with our announcement (to break up) and failed adequately to take into account the extraordinarily fragile market psychology and hostile environment that has distracted and damaged our business in recent months,” he said.