NAVAL STATION ROTA, Spain — Thousands of anti-military activists and environmentalists plan to protest within earshot of this base Sunday in an annual event expected to take on a boisterous anti-war theme.

The 18th “Marcha a Rota,” or March to Rota, might be the largest in years.

Busloads of protesters from Morocco, Portugal and Spain planned to arrive on the weekend to participate.

In the past, activists used the demonstrations to deliver scathing barbs directed at NATO and shout chants encouraging U.S. forces to leave bases in Portugal and Spain. This year, they will focus on the war in Iraq and Spain’s unwavering support for President Bush.

The naval station warned Americans this week to avoid the gathering and to tune into the base radio station for updates.

“We’re recommending all Americans stay away from this demonstration, take alternate routes and stay tuned to 102.5 FM,” base spokesman Chief Petty Officer Dan Smithyman said.

Security planned to possibly close two of the three base gates throughout most of the day Sunday, he added. The main gate that opens into downtown Rota will remain open. If needed, Spanish security could open an alternate gate so military personnel and civilian workers can enter and leave the base.

Spanish Prime Minister José Maria Aznar has sided with President Bush on Iraq even though the overwhelming majority of Spaniards remain adamantly opposed to war.

Some polls have shown that more than 80 percent of the nation is against the war.

Protests have been held throughout the country this past month, with the largest demonstrations held in the Madrid and Barcelona.

Although the naval station is the largest employer in Rota and nearby El Puerto de Santa Maria, banners deploring the war hang from balconies downtown and outside residential homes.

This past week, activists have held 30-minute anti-war protests each night, but they have attracted no more than a couple dozen people. Earlier this month, Greenpeace activists tried to block the naval station’s port entrance with the group’s flagship, Rainbow Warrior. Spanish Civil Guard stormed the ship, took its anchor and towed the schooner to the nearby port city of Cadiz, where the ship remains.

Sunday’s annual march could attract 10,000 or more protesters. The protest march starts at noon in El Puerto de Santa Maria and will end about a mile from the Fuentebravia gate — a popular entryway for Americans who live in base housing.

Some regional politicians who have been critical of Madrid have encouraged participation in the march while demanding that U.S. warplanes involved in the war on Iraq not use Spanish bases.

Deputies in Spain’s ruling party scuttled a motion by opposition members on Monday to prohibit U.S. forces from using the bases and airspace.

More than 3,000 American servicemembers are stationed at Naval Station Rota, north of Cádiz, and Morón Air Base, southeast of Seville. About 1,200 U.S. military personnel are stationed at Lajes Field in the Portuguese Azores.

In addition, NATO has commands in Lisbon, Madrid and Valencia, Spain.

The Spanish government has allowed the U.S. to use its bases and airspace but have prohibited any direct attacks on Iraq from the country.

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