Large areas of the northern Nicaraguan mountains have been cleared of civilians, according to government military officials, who say those wilderness areas are now strictly war zones in which the Sandinistas will increase their firepower.

On a recent trip beyond this town 120 miles north of Managua, I walked about seven miles into one of those newly militarized zones where until now the rebels had been able to find food, refuge, information and recruits.

The residents evacuated in the past two months were among at least 7,000 families that the Sandinistas say they are in the process of relocating to less remote areas.

According to local military officials, the road I followed is being improved to facilitate the Army's access to the mountainous zone, considered strategic because it is just across the border from Honduras and the largest of the rebel camps, called Las Vegas.

The spine of hills that runs out of Honduras and by Murra has been a principal thoroughfare for the contra rebels who enter Nicaragua from that camp, Sandinista officials say.

Houses along the road were abandoned and had been emptied of all possessions. In some cases, roofing material had been dragged away and the insides of the stripped houses were exposed to the elements. In other houses, bread ovens and primitive cooking stoves made of clay had been smashed to prevent use by the rebels.

There were no people to be seen. Chickens, pigs and cows, which normally surround such rural houses and which the rebels have been known to buy from farmers, were also gone.

On trees, the Sandinistas had posted a message telling the rebels that 1985 would be a year in which they "continue to be defeated" and offering them amnesty.

Entitled "A Letter of Return," the poster featured a drawing of a uniformed rebel turning in his rifle and being welcomed joyfully by his family.

"The Popular Sandinista Army agrees to respect your life, your physical integrity and agrees to give you just and dignified treatment if you deliver yourself with this document to our troops or to the nearest militia post with your rifle and your equipment," it said.

After almost two hours of walking, I rounded a bend and was stopped by the sound of a bullet being shifted to the chamber of a bolt-action rifle. No one was visible. As I raised my hands, a Sandinista soldier stepped out from behind a canvas lean-to farther up the road.

Lt. Felix Sanchez, who was at a makeshift camp around the next bend, said no civilians were to be in the area. He said the next Sandinista outpost, at an abandoned hamlet called Rosario overlooking the border, had been besieged last month by hundreds of rebels, and that 11 Sandinistas had died there.

Sanchez said his men, who patrol for three miles around their camp, taking them close to the border, had not seen a contra in two weeks.

"We think they are in Honduras reorganizing," he said. "They used to take advantage of people who lived in areas like this. They used to get food from them, but now they can't anymore and they are having to reorganize."

In an interview in Managua, Tomas Borge, minister in charge of internal security, said that with civilians removed from the area "it makes it easier to use our artillery. It clearly becomes a war zone."

Observers said they expect to see use of Soviet-made Mi24 helicopter gunships.

Asked if the Mi24 would be used in the new militarized zones, Borge said: "If such helicopters were here, it would be stupid to have them as museum pieces."

Borge said he expected rebel attacks soon in conjunction with a congressional vote on whether the United States should renew their funding.