OSLO, Norway (Reuters) -- A U.S.-Norwegian scientific rocket was launched from northern Norway early on Thursday, the first time since a similar rocket sparked fears in Russia that it was under nuclear attack in 1995.

A Black Brant XXII research rocket to study the Northern Lights atmospheric phenomenon lifted off at 0613 GMT from Norway's Andoeya Island base to a height of 1,360 km (850 miles), about 20 km higher than predicted.

Bad weather had delayed the flight for several days.

"Scientific conditions were ideal and all instruments aboard worked as they should. From our point of view this was a perfect launch," said Paul Kintner, Professor and Associate Director of Electrical Engineering at Cornell University.

The so-called CAPER (Cleft Accelerated Plasma Experimental Rocket) was of the same type that triggered a nuclear alert for Russian President Boris Yeltsin four years ago.

For a few minutes back then, the old Black Brant rocket prompted fears in Russia that a surprise attack was under way, leaving Yeltsin and his top aides to ponder a possible retaliatory strike.

The Norwegians said they had alerted all foreign embassies well before the launch, but the message apparently failed to reach Yeltsin or his top military staff.

This time, the Norwegian Foreign Ministry wrote to all embassies in Olso, including a hand delivered message in Moscow, to lay out details of the new four-stage rocket.

CAPER was funded by NASA and launched in collaboration with the Norwegian Space Agency, Adoeya Rocket Range, University at Svalbard (UNIS) and the University of Oslo.

American institution affiliations include Cornell University, the University of New Hampshire and the University of Alaska.

Copyright 1999 Reuters Limited. All rights reserved.