LONDON, May 27 (Reuters) - Gold imports to Switzerland from the United States jumped to the highest monthly level since at least 2012 in April after the exclusion of precious metals from U.S. import tariffs, Swiss customs data showed on Tuesday.

Switzerland, the world's biggest bullion refining and transit hub, and Britain, home to the world's largest over-the-counter gold trading hub, registered massive outflows to the U.S. over December-March as traders sought to hedge against the possibility of broad U.S. tariffs hitting bullion imports.

The Swiss data showed that gold imports from the U.S. rose to 63.0 metric tons in April from 25.5 tons in March. It was the highest in monthly data going back to early 2012.

Switzerland's total gold exports fell by 31% month on month in April with gold deliveries to the U.S. dropping to 12.7 tons from 103.3 tons in March.

Exports to the UK rose, indicating that gold was also coming from the U.S. back to London vaults via Swiss refineries.

Deliveries to traditional gold-consuming markets - India and China - rose month on month in April but remained below the level for April last year.

Swiss total gold exports and supplies to key markets* (in kgs):