A 28-year-old Bethesda man pleaded guilty in U.S. District Court yesterday to conspiracy to defraud the government and to making false statements in connection with a scheme to obtain false immigration documents for wealthy Iranians who wanted to live permanently in this country.

Hassan Hadj Mohammadi faces up to five years in prison and a $10,000 fine on each of the two charges, according to a Justice Department spokesman, who said Mohammadi is now cooperating with government prosecutors in the case.

No sentencing date has been set.

Mohammadi and three others named in a separate indictment were charged last September with conspiring to make payoffs to an Immigration and Naturalization Service official for his cooperation in securing permanent residence status for the Iranians.

The Justice spokesman said yesterday that the government's evidence against Mohammadi would show that Iranians were charged $8,000 to $19,000 per family for help in obtaining their documents and that "substantial" amounts of money were paid to the INS official. That official has not been charged with any offenses and is still working for the INS, the government has said.

The Justice spokesman said the evidence would show that Mohammadi helped bring four persons into the United States.