Mrs Arroyo and other government officials are accused of siphoning off money from a 728 million pesos (S$20 million) fund purportedly created to purchase fertiliser for farmers. She has denied any wrongdoing.

The allegations are part of an impeachment complaint against Mrs Arroyo filed by opposition lawmakers in the House of Representatives last month. The House hasn't acted on the complaint.

Testifying at a Senate hearing, former Agriculture Undersecretary Jocelyn 'Joc-Joc' Bolante said the fertiliser fund was part of the regular budget and therefore did not need Mrs Arroyo's approval to be disbursed.

A preliminary report by two Senate committees said there were indications the fund was only set up to 'suit (an) electoral purpose' and was never actually intended to buy fertiliser.

The report said Mr Bolante was the 'architect' of the programme.

Opposition Senator Manuel Roxas III called Mr Bolante's testimony 'lies'.

'We all know that nothing moves in this government without the knowledge of the highest official of the land,' he said.

Mrs Arroyo, who was swept to power in 2001 after President Joseph Estrada was ousted by a nonviolent 'people power' revolt, has survived four attempted power grabs and three earlier impeachment bids that included allegations she cheated in the 2004 elections.

Mr Bolante initially evaded the Senate investigation by fleeing in 2006 to the United States, where he unsuccessfully sought political asylum. He was deported to Manila last month. -- AP