KINGSTON, Jamaica (AP) _ U.S. officials have fined Air Jamaica $800,000 after marijuana was discovered on two of the airline's planes last week at Kennedy International Airport in New York, a government official said Saturday.

Transport Minister Pearnel Charles said Aer Lingus employees found 50 pounds of marijuana on Oct. 18 and U.S. Customs agents discovered another 50 pounds Oct. 21.

Air Jamaica leases a plane from Aer Lingus, Ireland's national airline.

Despite increased security at Jamaica's two international airports, marijuana has continued to be shipped to the United States on commercial and cargo flights, Charles said.

''This trafficking in marijuana is causing massive sums of money to be charged to the airline, great embarrassment to the Jamaican government and people and inconvenience to the traveling public,'' he said.

Since January 1984, Air Jamaica has been fined more than $7 million for bringing drugs into the United States, according to government figures.