NEW YORK (Thomson Reuters Foundation) - A dozen delivery and supply companies and affiliates based in Turkey are banned from doing business with the U.S. government due to their roles in profiteering from humanitarian aid intended for Syria, U.S. officials said on Friday.

A corrupt network of bribery, fraud, bid-rigging and kickbacks involving aid to Syria has been the subject of a two-year investigation, said the U.S. Agency for International Development (USAID) Office of Inspector General (OIG).

With the barring of Turkey’s Senkardes Co., its owner Orhan Senkardes and 10 affiliates, the probe has resulted in 35 suspensions and debarments, the OIG said in a statement.

The debarments announced on Friday will be in place for five years, officials said. The companies provided food kits, humanitarian items and delivery services related to USAID humanitarian programs in Syria.

The OIG disclosed last year that it had unearthed a corrupt network of commercial vendors, employees of nongovernmental organizations and others operating out of Turkey.

The most common fraud involved collusion between companies selling humanitarian supplies and staff of USAID local partners who accepted bribes or kickbacks in exchange for help in winning a contract.

There were also cases of aid items being substituted for cheaper alternatives and of inspection failures.

U.S. officials said the investigation found Orhan Senkardes, Senkardes Co and others participated in a procurement fraud scheme with corrupt NGO staff.

Four companies under Senkardes’ control also illegally bid against each other for U.S.-funded procurements, it said. Collusion in bidding violates federal regulations.

Since the conflict in Syria began in 2011, almost 500,000 people are estimated to have been killed and more than 11 million, about half the population, are displaced either internally or as refugees.

“OIG’s pursuit of corrupt actors in Syria and the surrounding region remains as critical as ever as we work to protect life-saving aid programs from fraud, waste, and

abuse,” said Ann Calvaresi Barr, USAID Inspector General, in a statement.

The OIG said its investigation was open and ongoing.