Anti-Sandinista rebels, under new arrangements with the Honduran Army, have sent the bulk of their forces -- estimated to involve about 10,000 troops -- back across the border reequipped to resume consistent attacks against targets inside Nicaragua, according to their leaders.

The large-scale movement into Nicaragua, confirmed by Honduran and other sources here, is designed to end a seven-month period of relative inactivity imposed by the cutoff last year of CIA funding, rebel leaders said. It was financed with money received this spring from undisclosed sources outside the U.S. government and now translated into arms, ammunition and other equipment shipped through Honduras into the hands of combatants, they said.

The accelerated pace of anti-Sandinista guerrilla activity was dramatically demonstrated last week when one rebel squad controlled the town of La Trinidad on the Pan-American Highway for four hours and another inflicted more than 50 casualties in an attack on Army forces at Cuapa, east of Managua. The attacks, one on Nicaragua's main road a short drive from large Army installations in nearby Esteli and the other deep inside the country, were seen as bold declarations of rebel strength in regions the Popular Sandinista Army has taken great pains to control.

"Cuapa is clear on the other side of the country from the Honduran border," said Alfonso Robelo, a member of the latest guerrilla umbrella leadership, the Nicaraguan Opposition Union. "This is very important."

The guerrillas' reequipping had nothing to do with $27 million in nonmilitary aid for the insurgent movement provided last month by Congress, rebel leaders said. It is still unclear what that money can be spent on and what part of the U.S. government will administer it here and in Washington.

But the rebel leaders voiced confidence that the congressional action will help them expand and maintain their forces in Nicaragua. The new legislation will provide direct funds for some needs, they said, and what they interpret as the open U.S. political endorsement symbolized by the congressional vote also will smooth the way for efforts to obtain military aid elsewhere.

Adolfo Calero, chief political figure of the Nicaraguan Democratic Force, the largest rebel group, said rebel leaders already have found enough money to resume attacks inside Nicaragua and maintain the consistent presence there that his forces were forced to abandon last winter. Calero said, for example, that he bought 5,000 G3 automatic rifles on credit earlier this year and since has purchased and shipped ammunition for these weapons, for the rebels' AK47 assault rifles and for support weapons such as rocket-propelled grenade launchers and mortars.

About 50,000 pounds of supplies, amounting to nearly a million rounds of ammunition, have been shipped inside Nicaragua in the past few weeks, he said. Honduran and other sources said the Nicaraguan Democratic Force had been using a recently acquired DC4 cargo plane to aid in the transport, a larger craft than the battered C47s that have been the guerrillas' main transport plane. An unmarked DC4 was seen this week at Tegucigalpa's Toncontin International Airport.

Calero and Frank Arana, the Nicaraguan Democratic Force's spokesman here, said their group has more than 17,000 combatants, with enough guns on hand to equip another 5,000. About 15,000 have moved inside Nicaragua, Arana said.

Calero has predicted the rebels will double their forces this year. Reports from Washington say Reagan administration officials also have expressed hope the insurgency will grow now that Congress has voted to support it again.

Honduran and other informed sources here put the number of Nicaraguan Democratic Force combatants inside Nicaragua at about 10,000, with several thousand more in a string of camps in the southern Honduran provinces of El Paraiso and Olancho. Miskito Indian groups and the Costa Rica-based former Sandinista commander, Eden Pastora, also have smaller forces under separate commands along the northeastern and southern Nicaraguan borders.

The former Nicaraguan Democratic Force headquarters camp at Las Vegas in El Paraiso province was closed last June by the Honduran Army, which has confined rebel forces to smaller camps more removed from Honduran towns and villages, the sources said. Relocation of the anti-Sandinista forces and renewed emphasis on keeping them within Nicaragua were part of a concerted Honduran Army effort to increase controls over rebel operations here, these sources explained.

Honduran Army fears about what may happen if the rebel forces run out of money have diminished since Congress voted to continue aiding the insurgent effort, they said. In addition, President Roberto Suazo Cordova's visit to Washington in May led to accords that have left the Honduran military more comfortable with the U.S. and rebel presence here, including an agreement ending the diplomatic status of about 1,000 U.S. troops consistently stationed here.

But the Army has increased controls as part of its policy of helping the guerrillas, they added. A Honduran source said, for example, that the Honduran Army had set up a special command center to monitor rebel activities here and has expelled several combatants in recent months for violating Army rules.

This does not reflect Army opposition to the insurgents but rather concern to keep Honduran control over their activities on Honduran soil, he said.

The return of U.S. accounting, inspection and other controls, likely to accompany disbursement of the recently voted $27 million, could clash with the Honduran concerns, the source said.