A former Fiji military leader who has fled to Tonga wants Fijians to "stand up" to interim Prime Minister Frank Bainimarama and claims the army would not turn its guns on the people to defend the regime.

Fiji yesterday started extradition proceedings to have Lieutenant-Colonel Ratu Tevita Mara returned from Tonga, where he is being housed by the King after a Tongan Navy vessel picked him up at sea last week.

The former Bainimarama supporter is on bail on a charge of making a seditious comment and due back in court on May 30.

Commodore Bainimarama has reacted angrily to Colonel Mara being spirited out of the country and has begun a police hunt for anyone who helped him leave, saying it showed "a fundamental disloyalty to Fiji".

Yesterday, Colonel Mara said he left so he could force a regime change in a country he now compared to Nazi Germany where someone could be charged for voicing mild criticism in a private conversation.

He told the Fiji-based Coup Fourpointfive blog the regime's leaders now had the "look of desperation".

"They all know their time is numbered. It is time for the people of Fiji to realise that they can stand up.

"They can be sure no soldier will shoot a fellow Fijian ... to protect the evil [Attorney-General Aiyaz Sayed-] Khaiyum and his ignorant puppet Bainimarama. Democracy will return to Fiji soon."

Colonel Mara was a key figure in the December 2006 coup, when he commanded the Fiji army's third infantry regiment.

He said he intended to return to Fiji to answer to the people for his own actions in that coup.

However, he would continue to criticise the regime until then.

"I have left Fiji to force regime change. Khaiyum and his puppet Bainimarama must go."

Colonel Mara said he did not fear the extradition proceedings as he was now in a country where he could expect a fair trial.

"I am confident the law will protect me from extradition."

New Zealand is remaining at arm's length, saying it is up to the two countries involved to resolve the dispute.

Prime Minister John Key said New Zealand did not want to escalate tension and was reassured by Tonga's statement that the independent judiciary would prevail.

Foreign Minister Murray McCully said he was watching the affair closely to ensure it did not affect regional stability but did not believe intervention would be helpful.

Commodore Bainimarama said Colonel Mara's departure was "an act of a despicable nature" and urged Tonga not to risk damaging the close relations between the two countries by sheltering him.

He also claimed Colonel Mara was being investigated over alleged missing funds from Fiji Pine - an investigation Colonel Mara said he did not know about and was an attempt to smear his name.

Colonel Mara is the son of Fiji's first Prime Minister, the late Ratu Sir Kamisese Mara. He is also the brother-in-law of the current President, Ratu Epeli Nailatikau, and has family links to the Tongan royals.

The tension between Tonga and Fiji rose yesterday but both countries said they hoped to maintain a strong relationship.

Commodore Bainimarama accused Tonga of breaching Fiji's sovereignty by entering its waters and protecting a "fugitive".

Tonga's Prime Minister, Lord Tu'ivakano, rejected any claim the kingdom was giving immunity to Colonel Mara, saying its courts would be free to decide on the extradition application without interference from the King or Parliament.

He said it was offensive to imply "for political gain" that the King's offer of hospitality to a "kinsman" amounted to an offer of immunity.

Tonga has also denied entering Fiji's waters to collect Colonel Mara. Yesterday, he said he had been out fishing when he got into difficulties and was picked up by the Tongan Navy.