Britain had decided to defer consideration of selling arms to Somalia because of the fighting in the Ogaden region, British officials said yesterday in London.

They said that eventual arms sales, when the situation in the disputed Ogaden had settled, have not been ruled out.

Earlier this week the United States and France announced that they would delay promised weapons deliveries to Somalia because of the Ogaden fighting.

The Ethiopian news agency said, meanwhile, the Ethiopian American-built F-5 jets shot down two Somali Mig-21s over Jigjiga in the Ogaden region.

"After successfully accomplishing their various mission," the Ethiopian news agency said, the F5s "performed aerial acrobatics for the benefit of the enemy forces concentrated in the area."

There were reports yesterday that the Soviet Union has agreed to supply Ethiopia's beleaguered military rulers with 48 Mig-21 fighters, modern tanks and missiles under a secret $385 million arms deal.

The reports came from Western military sources in Beirut and a spokesman for the Damascus-based Eritrean Liberation Front-Revolutionary Council, one of three guerrilla movements fighting for the independence of Ethiopia's northernmost province, Eritrea.

Last spring, after the Soviet Union and Ethiopia first established a formal alliance, there were reports that the Soviets were shipping arms amounting to more than $100 million to Ethiopia.