WASHINGTON – Radio spots promoting a $25 million reward for information leading to the capture of Osama bin Laden and another $25 million for his deputy, Ayman al-Zawahiri, are airing in the rural mountains of northwest Pakistan for the first time this week.

Television ads promising that fortune in return for bin Laden ran on two Pakistani stations last weekend, and will run regularly on Pakistan’s biggest station starting Tuesday.

Last month, newspaper ads appeared for the first time in the country’s major cities featuring the faces of bin Laden, al-Zawahiri and other top al Qaeda lieutenants.

The ads are the result of legislation written by U.S. Rep. Mark Kirk, R-Ill., and pushed into law late last year by fellow Illinois Republican Rep. Henry Hyde, chairman of the House International Relations Committee.

The two took action after learning that little had been done since the Sept. 11 terrorist attacks to publicize the rewards program aimed at capturing al Qaeda’s leaders where they are believed to be hiding.

On a trip to Islamabad in January 2004, Kirk visited the U.S. Embassy and asked then-Ambassador Nancy Powell who was overseeing the publicity for the rewards program.

“The ambassador said, ‘I don’t know who is working the rewards program,’ which was stunning to me,” Kirk said.

There were no radio ads about the program, even on the Voice of America station where they cost the government nothing, said a staff member, who asked not to be named. “We came back saying, ‘What a disaster,’ ” he said. A State Department spokesman had no comment on why the rewards program was not being publicized in Pakistan or Afghanistan in the years after the Sept. 11 attacks, but said the department’s approach has changed.

So far, the United States has spent $100,000 on the advertising.

In the days after the first newspaper ads hit the streets in January, two people provided tips about bin Laden’s whereabouts that are being vetted, the International Relations Committee staff member said.

Kirk and Hyde’s measure also enables President Bush to sweeten the pot; it authorizes him to increase the bounty on bin Laden to $50 million, although Bush has yet to exercise that power.

More important, Kirk believes, it also made the reward more flexible and comprehensible to the rural Pakistani tribesmen he hopes will one day turn over bin Laden: Payments can be in farm equipment and livestock as well as new trucks and motorcycles.

“In some parts of the world people understand what a herd of cattle or herd of goats means,” the State Department spokesman said. “That’s more realistic to them than a number such as $25 million.”