RIO DE JANEIRO, Brazil (AP) _ Oil workers have gone on strike for higher pay, threatening to paralyze refining and production in this nation of 150 million.

Fronape, Petrobras' tanker fleet, also joined the strike that began Wednesday, but a spokesman said exports would not be effected by the stoppage.

''The strike only effects workers on land,'' said the spokesman, who asked not to be identified. ''Maritime operations will not be interrupted.''

Strike leaders said 95 percent of Brazil's 55,000 petroleum workers had joined the walkout after midnight Tuesday.

''We have stopped shift changes at refineries, and they should be totally paralyzed by tomorrow,'' Heitor Lermen of the national strike headquarters said by telephone.

Brazil exports refined petroleum products, including gasoline to the U.S. east coast.

Petrobras, the government oil monopoly, said it had no information on the extent of the strike. But on Tuesday, a Petrobras spokesman said Brazil could cut back exports if the strike dragged on.

''Our priority is to supply the internal market,'' Lucio Pimentel said. ''If the strike is prolonged exports could be cut back.''

Lermen said production had been reduced on offshore rigs in the Campos Basin, which accounts for about 60 percent of the 673,000 barrels of oil Brazil produces daily.

On Tuesday, the 19 oil workers' unions rejected a last-ditch offer from Petrobras to avert a strike.

The unions are demanding a raise of 371 percent to offset inflation, plus job stability, reinstatement of 800 fired workers and the end of plans to ''privatize'' Petrobras. Prices last month rose 15 percent.

The company offered a pay increase of 80 percent, Lermen said.

Lermen said stocks of oil products were enough for about 10 days. Petrobras declined to reveal the level of stocks, claiming the information was a ''weapon'' in the strike.

Since August, Brazil's 10 refineries have been operating at maximum capacity, processing about 1.4 million barrels of oil a day. Brazil produces about 60 percent of the oil it consumes.