Former prime minister Najib Abdul Razak said he can no longer speak freely about the 1MDB affair following the 21 charges laid against him.

Najib said even though the Kuala Lumpur Sessions Court had refused the prosecution's request to impose a gag order on discussing his case at public events and on social media, it was still a court matter.

"Alhamdulillah, the judge rejected both conditions and I was released on bail the same day.

"But with the charges in court, my opportunity to publicly comment on and explain the 1MDB issue outside of court is now limited," he said in a Facebook posting.

Najib was on Sept 20 slapped with 21 charges of abuse of power and money laundering in relation to the US$681 million he received in 2013, purportedly from 1MDB.

Najib said he will clear his name in court.

"With a fair judiciary that upholds the truth, I am confident it would be the best opportunity to put an end to the RM2.6 billion issue that has dragged on for years once and for all," he said.

The RM2.6 billion refers to the US$681 million based on the exchange rate when it was first exposed in July 2015 as having being found in Najib's personal accounts.