A Senate investigative committee may summon the head of the nation's largest Indian tribe to address allegations he accepted cash payments and favors from contractors seeking work on its reservation.

Sen. Dennis DeConcini, D-Ariz., said after Thursday's committee session that he is "pursuing" the question of whether to invite Navajo Chairman Peter MacDonald to testify before the panel, and whether to subpoena him if necessary.A special investigative committee of the Senate Select Committee on Indian Affairs has been holding hearings all week in which allegations have been made of corruption and mismanagement in federal Indian programs and on reservations. The investigation was inspired by a series of reports in The Arizona Republic and other publications.

Two white construction company owners and a Navajo contractor, testifying under immunity, spoke Thursday of free airplane rides, cash payments and other favors they gave MacDonald in hopes of increasing their business on the 25,000-square-mile Navajo Nation reservation in northeastern Arizona and adjoining parts of Utah and New Mexico.

They and another Indian construction official also said it was common for non-Indians to create dummy companies headed by Indians in order to qualify for federally financed projects set aside for members of the minority group.

Tribal spokeswoman Tazbah McCullah, speaking from tribal offices in Window Rock, Ariz., said the accounts of fraud and abuse made during the week were "malicious allegations" designed to "discredit the integrity of the Navajo nation, its people, government and sovereignty."

She said a delegation of 11 tribal officials would travel to Washington, perhaps by Monday, to testify to the Senate panel.