The 1987 International Sugar Agreement was ratified Thursday and brought into force at a meeting held here under United Nations auspices.

The new ISA is due to run until the end of 1990 and can be extended for a maximum of two years beyond that date, said Kelvin Scott, U.N. representative and secretary of the meeting.The International Sugar Organization Council was meeting at press time Thursday to discuss the organization's budget and to appoint its new officials. The ISA, like its precursor, is merely an administrative agreement with no economic provisions.

Twenty exporting countries, nine importing countries and the 12-nation European Community were present to ratify the agreement. The signatories accounted for 64.2 percent of the total voting strength of the ISO.

Five other exporting countries - Congo, Honduras, Pakistan, Swaziland and Panama - had expressed their intentions to join but were not present, delegates said. These countries may take steps to join the agreement at a later date, they said.

The only notable absentee from the agreement was Brazil, which has given no indications whether it will sign the agreement or not, ISO Secretary Constantin Politoff said. However, the fact that it has not given any indication of its intentions to the U.N. has not had any deleterious effect on the agreement, he added.