The former president of East Timor wants to give evidence on behalf of two Australians charged with sharing secret information.
Xanana Gusmao has warned his evidence is likely to embarrass the Australian government, renewing calls for Canberra to drop the prosecutions instead.
Former spy Witness K and lawyer Bernard Collaery are facing jail for allegedly sharing secret information with the government of East Timor, in relation to the 2004 bugging of the prime minister's office in Dili by Australian foreign agents.
"I already promised to them, if it was not a secret trial, I will go to be their witness," Mr Gusmao told the ABC.
When asked what he would reveal in court, Mr Gusmao said: "All the information that I know."
Witness K has indicated he intends to plead guilty for allegedly conspiring to share secret information with East Timor over the spying operation.
He is due to appear before the ACT Magistrates Court on Thursday.
Collaery intends to fight the charges against him. He is due back in court in December.