WASHINGTON -- In a blow to some American efforts to set the stage for business ties with Cuba, the Treasury Department has notified a Washington consultant that a conference between U.S. executives and Cuban officials would violate U.S. sanctions.

The Sept. 9-13 U.S.-Cuba business summit has been billed by its organizer, Alamar Associates, as ``a unique opportunity to stay in Havana and meet privately with Cuban officials and specialists who deal in your business.'' The cost was listed as $3,250 per person, including an overnight stay in Havana following a meeting in the Mexican resort of Cancun.

Ricardo Alarcon, president of the Cuban National Assembly, was listed as a guest speaker.

But, according to Clinton administration sources, the Treasury Department's Office of Foreign Asset Control (OFAC) notified Alamar owner Kiry Jones on Thursday that it had ruled the conference would violate U.S. sanctions against Cuba.

A State Department official, who spoke on condition that he not be named, hailed the OFAC ruling as ``fully consistent with U.S. policy regarding Cuba.''

``Our position remains crystal clear. We do not support such activities,'' the official said. ``Doing business with Castro's Cuba only reinforces the Cuban government's resistance to meaningful change and is a disservice to the Cuban people.

``Visits such as the one planned do not benefit the Cuban people, who are being denied their fundamental freedoms and opportunity to pursue private enterprise in order to enjoy the prosperity they so richly deserve.''

It was not clear whether the conference would still be held. Alamar Associates' Jones did not return repeated telephone calls to his Washington-based agency on Friday.

Jones sponsored an earlier business summit in March, with more than 50 U.S. executives visiting Havana, but not staying overnight.

U.S. government officials had earlier characterized OFAC interest in the summit as focusing on whether the Havana portion was ``fully host-funded,'' meaning the Cuban government was picking up the tab for all island activities because the U.S. embargo prohibits most Americans from spending dollars in Cuba.

In March the Clinton administration instructed OFAC to look more closely at claims of host funding.

``We are mystified how the Cuban government, given its own admissions of economic difficulties, can spare the funds to `fully host' such events,'' said the State Department official who praised the OFAC decision.

OFAC refused to disclose the content of its letter to Jones. But the State Department official said: ``OFAC pointed out that under existing regulations, regardless of whether it's hosted or not, their activities in promoting or arranging a meeting with [Cuban] ministry officials are impermissible as inconsistent with U.S. policy.''