Nepal's lawyers have decided to boycott a controversial probe agency formed by King Gyanendra, calling it illegal and unconstitutional.

The lawyers have decided not to plead any case before the Royal Commission for Corruption Control.

The commission was formed by Gyanendra with handpicked former bureaucrats in February after he dismissed the government of prime minister Sher Bahadur Deuba and imposed emergency.

But the king's critics - especially Nepal's opposition parties - feared the agency would be used to settle political scores and repress political leaders as it has been given the unprecedented power of charging, trying and convicting, all on its own.

Its boycott by lawyers comes after Nepal's apex court, the Supreme Court, Wednesday refused to accept a challenge by an independent lawyer.

Nepalese advocate Bharat Mani Gautam tried to start a case against the commission, saying it was illegal since it was formed under one provision of the constitution and then given a fresh lease of life under another provision.

However, the registrar of the Supreme Court refused to accept the petition, saying the constitution did not allow any act by the king to be questioned.

"This shows the king is above the judiciary as well as the constitution," said Shrihari Arryal, senior lawyer and chief legal advisor of Deuba's Nepali Congress (Democratic) party.

"The constitution has no provision for the king to head the government. Since this government is extra-constitutional, the courts have lost their independence."

Nepal's lawyers, banded under the Nepal Bar Association, an independent body that had been urging the Supreme Court to release detainees held during emergency, have decided not to plead before the commission.

Immediately after its formation, the commission started investigating eight ministers of the deposed government, including Deuba himself.

The former ministers have been accused of distributing money illegally among party cadre from a government fund intended for the rehabilitation of victims of natural calamities and the escalating communist insurgency.

Deuba and another former minister, Prakash Man Singh, who held the physical planning and works portfolio, have also been accused of unduly favouring a contractor in a multimillion-rupee drinking water project aided by the Asian Development Bank, the World Bank and other donor agencies.

After Deuba and Singh refused to heed the commission's summons to appear before it for questioning, saying they considered the panel to be illegal and politically motivated, both were arrested.

Deuba's arrest especially triggered international condemnation since the three-time former prime minister was forcibly taken away from his residence in a midnight raid by security personnel who also sealed off the road and cut his power and telephone lines.

Deuba and Singh have refused to hire lawyers to defend themselves before the commission.

The royal watchdog came in for further criticism last week when the king lifted the state of emergency but instead of disbanding the panel gave it a fresh lease of life under a different provision of the constitution.