"The net is closing" around those who support terrorists around the world, President Bush said in the White House Rose Garden. "Today it just got tighter."
Mr. Bush spoke hours after the administration froze assets and shut offices related to an American Islamic foundation and two overseas groups accused of financing Hamas' activities.
Hamas, a militant group which opposes Israel's existence, claimed responsibility for three suicide bombings in Israel over the weekend that marked one of the deadliest phases in the 14-month Palestinian uprising against Israeli occupation.
The bombings prompted retaliation by Israel, which on Tuesday attacked Palestinian cities across the West Bank and Gaza Strip, hitting just beyond Palestinian President Yasser Arafat's main West Bank headquarters while he was inside. Arafat was not hurt.
The multiple bombardment by Israeli warplanes and helicopter gunships was the largest simultaneous air strike at Palestinian targets since the start of the uprising.
The White House declined comment on any actions that Mr. Bush might take against the three groups, saying only that the president would make a statement on "the financial aspects of terrorism."
Ranaan Gissin, a Sharon aide, welcomed the U.S. action as a way of "cutting off the umbilical cord of terrorist groups."
But a Hamas spokesman in the West Bank town of Nablus, Tasir Imran, denied the groups were funneling Hamas money and called the U.S. move "part of the war against the Palestinian people." The Americans "want to support Israel in its siege and restrictions against our people," Imran said.
As part of its campaign against global terrorism following the Sept. 11 attacks on New York and Washington, the United States and its allies have already taken several steps to disrupt the financing of suspected terrorist groups.
Israeli attacks on Palestinian targets.
Since Sept. 11, the United States has tightened laws to control money laundering, has ordered a freeze on assets of suspected individuals and organizations and has closed money-transfer businesses suspected of aiding targeted groups.
One organization targeted in the crackdown claims to be the largest Muslim charity in the United States, reports CBS News Correspondent Sharyl Attkisson.
Based in Texas, The Holy Land Fondation for Relief and Development masqueraded as a charity but existed to promote terror, according to the Bush administration.
But Shukri Abu-Baker, the president of the organization, denied the accusations. "We are innocent. The Holy Land Foundation has no relationship with terrorism," said Abu-Baker. "We have not funded any terrorist activities."
But Treasury investigators said some of the $13 million Holy Land raised in the country last year went to recruit and support suicide bombers and even paid out death benefits to their widows. Tuesday, offices in four states were shut down.
It is the third time since October that the administration has frozen assets of groups suspected of aiding terrorists.
The two financial groups targeted Tuesday, both based in Palestinian-controlled territory, are Al Aqsa International Bank and the Beit El-Mal Holdings Co., an investment group. It was unclear whether either group had assets in the United States, but the administration was urging allies to freeze the organizations' holdings.
The administration had planned the crackdown for later in the month, but moved up the action after the weekend suicide bombings in Israel that killed 26 people. The schedule change scuttled administration plans for coordinated action by its allies, officials said.
Al Aqsa International Bank was founded in 1997 with $20 million in capital, but did not begin operating until September 1999, according to administration officials. The bank is owned by the Jordanian Islamic Bank and by Beit El-Mal. Many of the same people who run Al Aqsa bank also control Beit El-Mal, officials said.
Israel outlawed Beit El-Mal in May 1998, accusing it of being tied to Hamas.
©MMI, CBS Worldwide Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press and Reuters Limited contributed to this report