The U.S. Navy notified Puerto Rico's government on Friday that it will resume military exercises on the outlying island of Vieques next month.

The training exercises could begin as early as April 1 and will last about 22 days, Capt. G.H. Cooper said in a letter to the U.S. territory's secretary of state, Ferdinand Mercado.

Only inert bombs are to be used at the firing range on the island's eastern tip. The last round of exercises on Vieques was held in September and October.

The Navy stopped using live bombs on Vieques after off-target bombs killed a civilian guard on the range in 1999, triggering mass demonstrations.

Opponents have charged that the bombing harms the environment and health of Vieques' 9,100 residents — accusations the Navy denies.

The Navy has bombed the Vieques firing range for six decades, training troops for conflicts from World War II to the Gulf War.

Islanders were supposed to vote in a binding November referendum to decide whether the Navy should continue bombing on Vieques, but Congress canceled the vote, leaving the question of when the military would withdraw up to Navy Secretary Gordon England.

President Bush has said the Navy should stop using Vieques by May 2003.