BURBANK, 23 August 2003 — The United States yesterday froze the assets of six senior Hamas leaders and five European-based organizations it says raise money for the radical Palestinian group.

President George W. Bush said he was taking the action because Hamas claimed responsibility for Tuesday’s attack on a packed bus in Jerusalem that killed 20 people, including six children.

The move, being carried out by the Treasury Department, also targets six top Hamas leaders.

A senior administration official,speaking on condition of anonymity, said it was the first effort to block Hamas’ assets or funding sources outside the United States. Similar action has been taken worldwide against Al-Qaeda and other terrorist networks,however.

The Jerusalem bombing prompted a new round of Mideast violence.

“Hamas has reaffirmed that it is a terrorist organization committed to violence against Israelis and to undermining progress toward peace between Israel and the Palestinian people,” said Bush, who stopped here for an event about his salmon restoration policies during a two-day trip through the Pacific Northwest.

Bush called on “all nations supportive of peace in the Middle East” to recognize Hamas as a terrorist organization and to join the United States in freezing the groups’ funds.

The Treasury Department supplied the following names and identifications for the six individuals: Sheikh Ahmed Yassin, the leader of Hamas in Gaza; Imad Khalil Al-Alami, a member of the Hamas political bureau in Damascus, Syria; Usama Hamdan, a senior Hamas leader in Lebanon; Khalid Mishaal, head of the Hamas political bureau and executive committee in Damascus; Musa Abu Marzouk, deputy chief of the political bureau in Syria, and Abdelaziz Rantissi, a Hamas leader that Treasury described as reporting to Yassin.

The charities whose assets were frozen included a support group based in France called the Committee for Charity and Aid for the Palestinians; the Association for Palestinian Aid in Switzerland; the Palestinian Relief and Development Fund, or Interpal, headquartered in Britain; the Palestinian Association in Austria, and the Sanbil Association for Relief and Development, which is based in Lebanon.

The administration official said several European countries appear supportive of the asset freeze, but that the administration was waiting to see the official response.

The White House also reacted cautiously yesterday to the promised Israeli campaign against militant chiefs. “Our focus is on getting the parties back together so they can work to resolve these issues,” Bush spokesman Scott McClellan said.