The National Party has confirmed a formal complaint has been made against Deputy Prime Minister Barnaby Joyce.

Key points: Barnaby Joyce describes the allegation as "spurious and defamatory"

Barnaby Joyce describes the allegation as "spurious and defamatory" ABC told the complainant holds prominent role in the WA regions but is not a WA Nationals MP

ABC told the complainant holds prominent role in the WA regions but is not a WA Nationals MP The National Party federal director says all complaints are taken seriously

The ABC understands the complaint is in relation to allegation of sexual harassment involving a West Australian woman and Mr Joyce.

Mr Joyce said he had been "made indirectly aware" of the allegation and described the claim as "spurious and defamatory".

A spokesman for the Deputy Prime Minister said "allegations of wrongdoing should be immediately referred to police so that the veracity of any claim could be properly tested".

"All complaints are taken seriously and treated with the strict confidentiality and given due process," the National Party federal director Ben Hindmarsh said in a statement.

WA Police said they had not received a complaint about Mr Joyce.

The ABC has been told the ongoing issues surrounding Mr Joyce and his affair with a former staffer were discussed in a closed session of the WA Nationals State Council at Bindoon on Saturday.

On Tuesday, WA Nationals MPs then held a regular partyroom meeting where the sexual harassment complaint against Mr Joyce was raised.

The ABC has been told the complainant is not a WA Nationals MP or staffer but she holds a prominent role in the WA regions.

Nationals Minister Nigel Scullion was asked for his view on the allegation as the story broke, but told ABC Radio National he had not heard of the complaint.

Mr Joyce has taken leave to focus on his personal life, after it became public he was expecting a child with his former media adviser.