A front-runner for the Philippines 2004 presidential elections has resigned from the government over a corruption inquiry.

Raul Roco, Education Secretary, said the probe was humiliating and criticised President Gloria Arroyo for endorsing it.

Mr Roco has called the allegations baseless

"There is no place in a democracy for humiliating people as a policy instrument," he said in a statement.

It is the second high-level falling out to hit Mrs Arroyo's cabinet recently.

In July she engineered the sacking of former Foreign Minister Teofisto Guingona, prompting criticism of her style of leadership.

Mr Roco, a popular senator, is widely seen as a possible presidential candidate in 2004, when Mrs Arroyo is also expected to run.

An opinion poll published in the Philippine Daily Inquirer suggested Mr Roco was ahead in the race, with Mrs Arroyo third.

The corruption probe stems from allegations made by Department of Education employees against Mr Roco.

If I had been asked, I would have explained

Raul Roco

According to these claims, his wife was given a driver from the department, and he used public money to print posters promoting himself.

Mrs Arroyo endorsed a full investigation earlier this month. The Presidential Anti-Graft Commission is expected to complete its enquiry in two months.

Mr Roco told a radio interviewer: "The message here is that there is no confidence in me and if the president has no confidence in a cabinet member, that cabinet member will not be effective."

He said he had not spoken to Mrs Arroyo about the incident.

"I was not asked anything. If I had been asked, I would have explained," he said.