Rosmah Mansor, the wife of Prime Minister Najib Abdul Razak, has denied allegations circulating online accusing her of signing cheques as one "Eric Tan".

According to her lawyer NoorHajran Mohd Noor, the matter was in relation to a criminal case in Singapore involving former Falcon Bank branch manager Jens Fred Sturzenegger.

Checks with the statement of facts issued by Singapore's attorney-general's chambers does not corroborate with claims made against Rosmah online, she said.

"These allegations are serious, intended to make representations, publishes imputations intending to harm or knowing or having reasons to believe that such imputations will harm the reputation and done with malicious intent to destroy and reduce the credibility of Rosmah as the wife of the honourable prime minister," said NoorHajran.

Sturzenegger was sentenced to 28 weeks jail and fined S$128,000 after pleading guilty to six charges related to Singapore's probe on 1MDB related matters.