WASHINGTON, June 11 (Reuters) - The United States on

Tuesday imposed sanctions on Guyanese mining magnate Nazar

Mohamed and his son Azruddin over allegations they defrauded

Guyana's government of tax revenues and bribed public officials,

the Treasury Department said.

A company owned by the Mohameds was formerly part of a

consortium building a $300 million logistics base in the South

American country for oil giant Exxon Mobil Corp ( XOM ), but

their company pulled out after Reuters reported the pair was

facing criminal probes by U.S. law enforcement agencies.

The sanctions target three of the men's companies -

Mohamed's Enterprise, Hadi's World and Team Mohamed's Racing

team - as well as a Guyanese government official, Mae Thomas,

who the U.S. Treasury described as the country's Permanent

Secretary of the Ministry of Labor.

U.S. Treasury Department official Brian Nelson said the

action aimed to disrupt "those who seek to exploit Guyana's

underdeveloped gold sector for personal gain."

The sanctions were enforced by the Office of Foreign Assets

Control (OFAC), which is part of the U.S. Department of the

Treasury, and is the body responsible for applying economic and

trade sanctions. It blocks U.S. companies from doing business

with sanctioned parties.

The Treasury designation did not mention Exxon or its shore

base contract.

Exxon said its contract is with a consortium of businesses

of which Mohamed Enterprise has not been a part of since last

year.

"ExxonMobil ( XOM ) complies with all applicable laws and

regulations where we operate," it said in a statement. "Any

assertion to the contrary is ridiculous."

Guyana's government said on Tuesday it was seeking

additional information from the United States about the

sanctions, and had put Thomas on leave.

The Mohameds did not immediately reply to request for

comments, but have previously denied any wrongdoing.

US PROBE

U.S. government officials had warned Exxon in late 2021 and

early 2022 to avoid doing business with the Mohameds as they

faced U.S. investigations into money laundering, drug

trafficking and gold smuggling, Reuters reported last year,

citing five people with knowledge of the matter.

The Texas-based oil giant nonetheless announced a deal in

April 2022 to award the contract for the logistics base to a

consortium that included the two Guyanese businessmen.

The Mohameds exited the consortium in October 2023.

The decision to leave the contract was voluntary and

exclusively made by the Mohameds and their two Guyanese partners

in the Vreed-en-Hoop Shore Base Inc (VESHI), the entity uniting

the three Guyanese parties, NRG Holdings, said in October.

VESHI and NRG declined to comment. NRG said the shorebase,

designed to support Exxon's offshore activities, should be

inaugurated by the end of the year. The base was initially set

to open last year.

U.S. individuals and companies are prohibited from doing

business with individuals and entities on Treasury's sanctions

list, and must perform due diligence to ensure their customers,

suppliers and partners are not listed parties.

Violating the sanctions can result in fines and criminal

charges.

Between 2019 and 2023, Mohamed's Enterprise omitted more

than 10 thousand kilograms of gold from import and export

declarations and avoided paying more than $50 million in duty

taxes to the Government of Guyana, the U.S. Treasury said.

The U.S. said that Azruddin and Mohamed's Enterprise had

engaged in extensive bribery schemes involving government

officials in Guyana. This includes providing direct and

recurring bribery payments to Guyanese government officials to

ensure favorable treatment, including award of government

contracts, according to sanctions.

Mohamed's Enterprise had mostly focused on gold mining and

foreign currency exchange before expanding into the oil business

in recent years and securing a part in the lucrative deal with

Exxon.