HAMILTON, Bermuda (Reuters) - Hurricane Florence bashed Bermuda with powerful winds and pounding surf on Monday and gained some strength as it swept just offshore of the mid-Atlantic British island.

Florence's sustained winds grew from 80 mph (130 kph) to 90 mph (145 kph), and a wind gust was measured at 111 mph (180 kph) on the island, the U.S. National Hurricane Center said.

At 11 a.m. the center of the Atlantic season's second hurricane was about 60 miles northwest of Bermuda and moving north-northeast at 13 mph (21 kph).

The core of the Category 1 hurricane -- the lowest rank on the five-stage Saffir-Simpson scale -- stayed just off the Bermudan coast.

The hurricane was forecast to stay away from the North American mainland, but created heavy surf along parts of the eastern United States and the Canadian Maritime provinces.

Bermuda issued a hurricane warning and government leaders called up 200 troops and placed 250 more on standby for possible deployment after the storm.

Hundreds of emergency service workers were also on standby in the wealthy holiday destination, which is home to about 65,000 people and is an international finance center.

There were no immediate reports of injuries or serious damages from Florence, but the storm knocked out power to about 23,000 homes and businesses, a spokesman for the Bermuda Electric Light Company said.