Saudi Arabia offered Islamic militants a limited amnesty Wednesday, saying their lives would be spared if they surrendered but they would face the "full might" of state wrath if they did not.

The ultimatum, issued in the name of King Fahd, called on militants to turn themselves in within a month -- suggesting the kingdom was paving the way for a stepped up campaign against al-Qaida-linked fighters who have shaken the country with a series of deadly attacks.

At the same time, the Saudi foreign minister denounced calls by militant clergy for Saudis to travel to Iraq to join insurgents battling the U.S. military and its Iraqi allies.

Some have said that at least one of the guerrillas who killed and beheaded a South Korean hostage in Iraq this week may be Saudi, since the guerrilla spoke Arabic in what seemed to be a Saudi dialect.

The ultimatum was read by Crown Prince Abdullah, the king's half brother and the country's de facto ruler, using some of the fiercest language yet against militants.

Abdullah said the offer was open to anyone who has not yet been "arrested for carrying out terrorist acts."

"We are opening the door of amnesty ... to everyone who deviated from the path of right and committed a crime in the name of religion," the crown prince said.

"We swear by God that nothing will prevent us from striking with our full might, which we derive from relying on God," Abdullah said.

In Washington, State Department spokesman Richard Boucher refused to comment on the Saudi amnesty offer, saying, "This is a decision for the Saudi government to make."

Under the amnesty, only those who committed acts that hurt others would be prosecuted, and no one who turns himself in would face the death penalty.

Over the past year, as attacks in the country increased, the Saudi government has frequently urged Saudis to reject Islamic militant ideology, bringing "repentant" militant leaders onto state-run television to denounce violence.

But the beheading of American engineer Paul M. Johnson Jr., who was kidnapped in Riyadh on June 12, brought a vicious new edge to the attacks -- and heightened fears that the violence could drive out American and other Western workers vital to Saudi Arabia's oil and other industries.

Two other Americans and an Irish citizen were killed in the kingdom in the week before Johnson's slaying.

Source: CD/Agencies