The Australian Competition and Consumer Commission is investigating two of crooked former Labor minister Eddie Obeid's sons over their involvement in a tender process for a coal exploration licence over the family's Bylong Valley farm.

The consumer watchdog confirmed on Friday that it is investigating Moses Obeid and Paul Obeid over allegations of cartel conduct, where businesses secretly agree to act together instead of competing with each other.

Investigation: Moses Obeid pictured in Sydney. Credit:Nic Walker

The two men are seeking to challenge compulsory examination notices issued by the ACCC, which would compel them to co-operate with the watchdog's investigations by handing over documents and giving evidence in private. Their lawyers will appear in court later on Friday in a bid to set aside the notices.

"These examinations are part of the ACCC’s investigation into allegations of cartel conduct regarding the 2009 tender process conducted by the NSW Department of Trade and Investment (formerly the Department of Primary Industries) for an exploration mining licence over the Mount Penny coal tenement in the Bylong Valley," the commission said in a statement.