PARIS, NOV. 29 -- France today announced the dispatch of 150 paratroopers to Chad to bolster a French garrison in the capital and protect its expatriate community there as a three-week rebel offensive continued to gain momentum.

But French officials, reflecting reluctance by President Francois Mitterrand to perpetuate France's colonialist role as Africa's policeman, declared that the French troops would not join the fighting or attempt to defend the government of President Hissene Habre as they have done in the past.

Chad insists that the rebellion is being funded, armed and directed by Libya leader Col. Moammar Gadhafi, a view endorsed by the State Department, which declared Wednesday that the uprising was "the latest example of Libya's ongoing efforts to destabilize legitimate governments."

Libya has denied any involvement, and French officials emphasized that the latest eruption of civil war in Chad was motivated by an internal political vendetta, with one of Habre's many rivals attempting to seize power.

The latest rebellion in Chad was launched Nov. 10 by forces loyal to Idriss Deby, a former military adviser to Habre. Deby's troops have inflicted serious losses on government forces, killing as many as 3,000 soldiers and achieving rapid territorial gains as they move westward from their sanctuary near the Sudanese border toward the capital of Ndjamena, according to French sources.

A French Foreign Ministry spokesman said, "The situation is worsening, and the battles are becoming more severe." He said the rebel offensive was escalating in size and intensity, with "government forces encountering serious difficulties on the ground." Habre took personal command at the front last week and barely escaped capture by the rebels before returning to the safety of the capital, French officials said.

After an emergency cabinet meeting Wednesday, the French government decided to send a company of 150 foreign legionnaires to join 1,000 French soldiers already stationed there. The decision was taken to improve "the security of our troops and assure, if necessary, the protection of our nationals," a Defense Ministry spokesman said. An estimated 1,250 French civilians live and work in Chad. But the spokesman stressed that French forces would in no way become involved in the conflict and did not perceive their mission as maintaining the Habre government in power.

In 1986, after Libya occupied a northern strip of Chad, France sent thousands of troops to help Habre push Gadhafi's forces back across the recognized border. Libya and Chad signed a peace treaty last year.