WASHINGTON, Sept 17 (AFP) - US President George W. Bush was to visit an Islamic center here Monday and assail violence against US Muslims in the wake of last week's terror strikes on New York and Washington, his spokesman said.

Following the attacks, which Bush and other top officials have pinned on Saudi extremist Osama bin Laden, one US Islamic advocacy group said it had recorded several hundred incidents of harassment, threats or violence.

"It is a leadership test ... to speak out and tell people and remind people that Muslim-Americans and Arab-Americans love this country, too," Ari Fleischer told reporters ahead of the mid-afternoon visit.

"No matter where someone comes from or when they got here, they are just as American, and they love our country just as much as everyone else. That's true in times of war just as much as it is true in times of peace, but it needs to be said more often in times of war, and that's why the president is going," he said.

The Council on American-Islamic Relations has recorded more than 300 incidents of anti-Muslim harassment, threats, discrimination and violence since history's worst terrorist attack leveled the twin World Trade Center towers and damaged the Pentagon. A fourth hijacked flight crashed in western Pennsylvania, killing all onboard.

"Right now, we're considering bomb threats 'minor,' if you can believe it," said one CAIR official, who declined to be named. "Major" incidents include killings and stabbings -- actual violence rather than mere threats.

CAIR has been following investigations into two lethal shootings Saturday as possibly motivated by ethnicity or religion: a 49-year-old Sikh gas station owner in Mesa, Arizona, and a Dallas, Texas-area Pakistani Muslim store owner.

The Washington-based group said Monday it received reports of vehicles being rammed into Islamic centers in Ohio and Indiana and a bomb going off at the Islamic Center of San Diego.

"The bigoted acts of a small minority are creating an atmosphere of apprehension and fear in the American Muslim community" of roughly seven million people, said CAIR Executive Director Nihad Awad.

"I want to make it very clear: vigilante attacks and threats against Arab-Americans will not be tolerated," FBI director Robert Mueller warned during a public appearance Monday.

"Such acts of retaliation violate federal law and, more particularly, run counter to the very principles of equality and freedom upon which our nation is founded," he said.

"We, to date, have initiated 40 hate crimes investigations, involving reported attacks on Arab American citizens and institutions," said Mueller.