About 7,000 Miskito Indians, half the population in the northeastern corner of Nicaragua, have fled to neighboring Honduras in the last two weeks, apparently to avoid renewed fighting between Nicaraguan troops and U.S.-backed rebels, according to U.N. and Miskito officials in contact with the refugees.

The Miskitos' flight was overshadowed by news of the nearly simultaneous incursion by Nicaraguan troops into Honduras to attack rebel camps about 100 miles further west. But the Reagan administration considered sending Vice President Bush to Honduras last week to call attention to the Indians' flight, according to the State Department; and CIA Director William J. Casey cited the situation in a speech Sunday in the context of the administration's quest for renewed aid to the contras, or counterrevolutionaries.

Mick Van Prag, Washington spokesman for the United Nations High Commission on Refugees, said that as of Saturday, 2,900 Miskitos had registered with UNHCR workers in Honduras near the border, and that 4,000 to 4,500 more were expected to sign in early this week. An estimated 10,000 to 15,000 Miskitos had been living in Nicaraguan villages in the remote area, where renewed fighting broke out March 25.

Some of the refugees walked or paddled canoes for nearly three days, crossing the Coco River at waist-deep fords with children, chickens and dogs on their heads, according to reports.

There is confusion about details of the exodus, the second major Miskito evacuation from the region since mid-1984. The State Department said it began when Nicaraguan soldiers arrived March 25 at the Indian villages around Bilwaskarma, about 40 air miles up the Coco River from the coast. The soldiers were reportedly dressed as International Red Cross workers and driving a Red Cross vehicle.

When they began rounding up Miskito youths for service in the Sandinista army, fighting broke out, according to the State Department. The conflict quickly spread to other villages and to countryside strongholds of Kisan, the armed Miskito coalition allied with the contras, according to reports.

However, Armstrong Wiggins of the Indian group Misurasata, who is human rights coordinator for the Washington-based Indian Law Resource Center, said the Sandinistas were dressed as workers of the Nicaraguan Red Cross, not the international group. Some Miskitos left because "they don't have much to stay and defend," he said.

"Everybody's lying about this, the Sandinistas, the administration, the press -- everybody's trying to make political mileage out of the Indians," he said.

Some refugees reaching the camps said they had been expecting Kisan to call them out of Nicaragua shortly in any case because of bad conditions in the villages and because of rumors that the Sandinistas were going to return them to relocation camps .

A spokesman for the Nicaraguan Embassy, Manuel Cordero, denied that Sandinista troops had used any disguise and said they had not engaged in forced recruitment. He said an official truce with Kisan remains in effect, although he acknowledged that some Kisan forces may have been with contra units that did come under attack.

The State Department said Sandinista artillery bombarded Bilwaskarma and the village of Kum, 20 miles closer to the coast. No one had any firm casualty figures.