A half-brother of Osama bin Laden and a relative of a family suspected of funding his operations were identified Tuesday as investors in Hybridon Inc., a Cambridge-based biomedical company. But yesterday, the company’s CEO quickly distanced Hybridon from links to the suspected terrorist mastermind.

Both Yahia M.A. bin Laden and Abdelah bin Mahfouz own small shares of the company.

Bin Mahfouz is a relative of Khalid bin Mahfouz, a former president of Saudi Arabia’s National Commercial Bank (NCB) who has been accused of trying to wire funds to front organizations for Osama bin Laden, the prime suspect in the recent terrorist strikes on the U.S.

“On a fully diluted basis, Yahia now owns about 6 percent,” Hybridon CEO Stephen R. Seiler said yesterday.

Seiler said that Yahia bin Laden, as with the majority of bin Laden’s 51 siblings, has officially denounced his brother’s actions, and pointed to news reports which have said that the family does not fund Osama bin Laden’s activities.

Seiler also defended Hybridon’s bin Mafhouz connection. Medical Science Partners, which specializes in early-stage life sciences investments, was founded in 1988 in association with Harvard University, and formed Hybridon in 1991.

“[Mafhouz] is from a part of the family different from that which funds bin Laden,” Seiler said, adding, “Mahfouz was a 1993 investor in Medical Science Partners and bought stock through them and directly.”

Seiler was quick to say that the Boston Herald was “using outdated numbers” when it reported on Tuesday a 16 percent holding for bin Laden and a nearly 12 percent holding for bin Mahfouz in the company.

Last year bin Laden owned 13.5 percent of Hybridon and bin Mahfouz owned 13.3 percent, according to the U.S. Securities and Exchange Commission. Bin Mahfouz currently owns about 3 percent of the company, according to the Associated Press.

Hybridon, one of many biomedical companies which have emerged in Cambridge in the last decade, is developing medicine to combat cancer and bolster the human immune system, including “antisense” technology, which involves the design of synthetic DNA material to inhibit the body’s production of disease-causing protein.

Former NCB New York senior vice president and general manager Camille Chebeir is also on Hybridon’s board of directors, though Seiler said that Chebeir stopped working for the bank six years before it was linked to Osama bin Laden.

Chebeir is currently president of Sedco Securities Inc., “a company which manages investments of the bin Mafouz Saudi Arabian family,” according to the Hybridon website.

Stephen M. Walt, Belfer Professor of International Politics at the Kennedy School of Government, said there was no reason to assume other bin Laden family members were terrorists, and that the issue of where funds go was a tricky one produced by the new global economy.

“This whole problem shows how difficult it is to trace and cut off the covert money flows that help support the global terrorist organizations,” he said.

Bin Laden has other family connections to Boston.

One bin Laden brother, Sheik Bakr Mohammed bin Laden, in 1994 made two large scholarship donations to Harvard, while another relative, Mohammed M. bin Laden, owns six condominiums in the ritzy Flagship Wharf condominium complex in Charlestown.

—The Associated Press contributed to this report.