Blindspots in satellite coverage of potential battle areas has prompted the Pentagon to build a newer version of the U2 spy plane.

Maj. Michael Burch, Defense Department spokesman, said Tuesday night that initial plans call for building 25 of the reconnaissance jets that would be similar in design to the old U2s but renamed TR1s.

The new planes would cost $8.5 million each, Burch said, and the total program, including fitting the planes with sophisticated sensors and providing ground support, would cost $550 million.

The shooting down of U2 piloted by Francis Gary Powers over the Soviet Union in 1960 caused Soviet Premier Nikita S. Khurshchev to cancel a planned summit meeting with President Dwight D. Eisenhower.

Use of the U2 for spying was cut back because of its vulnerability to antiaircraft missiles and the development of spy satellites.

Burch said sensors would permit the planes to gather military information without actually flying over the area being checked. This would make it more flexible than the satellites, which might not be covering a specific area at the moment information was needed, he added.

Some would be flown in Western Europe along the border with Eastern Europe to obtain information about Soviet military strength in the region, Burch said.

Lockheed Corp. would be a primary contractor for the TR1s, he said, adding that the Pentagon has included $10.2 million in its budget for fiscal 1979, which starts Oct. 1 to prepare for producing the planes beginning in 1980.