The U.S. dollar lost ground on most international money markets yesterday, but gained against the British pound and the French franc in extremely thin pre-holiday trading.

The brightest spot for the American currency was London, where the pound dipped to $1.87, its lowest rate this year, compared with $1.8980 on Wednesday. But traders attributed the dollar's rise to a general lack of confidence in the British economic outlook rather than to its own strength.

The French franc's weakness was in part due to Bank of France efforts to keep the dollar from falling, which would make French exports uncompetitive in world markets.

All European foreign exchange and bullion markets, with the exception of Milan, are closed today in observance of Good Friday, and will be closed Monday as well.

Dealers said trading was thin yesterday as market participants shied away from taking positions in advance of a four-day holiday. Thin markets exaggerate currency movements, a New York dealer said, but he added that the "underlying trend was for a weaker dollar when markets reopen next week."

Gold slipped slightly after early gains to close in London at $179.375 an ounce, down from $180.75 Wednesday. In Zurich, erratic trading left gold at $180.625, only marginally higher than the previous day's $180.125 an ounce.

Late dollar rates in Europe yesterday included:

Frankfurt - 2.0395 West German marks, down from 2.0455.

Paris - 4.68 French francs, up from 4.6625.

Zurich - 1.9005 Swiss francs, down from 1.9195 francs.

Amsterdam - 2.180 Dutch guilders, down from 2.1895 guilders.

Milan - 854.70 Italian lire, down from 855.45 lire.

In Tokyo, the dollar hit an all-time low, closing at 230.025 yen. On Wednesday it had managed a slight gain to 230.925 yen. The Bank of Japan reportedly purchased $150 million to $200 million in order to support the American currency.