MANILA - Western election observers on Saturday criticised the Philippine government for "insufficient" openness as the country prepares to choose its next president with a new automated voting system.

The US-based National Democratic Institute mission said at the end of a week-long visit that it recognised "substantial efforts" are being made to improve on previous elections, which it said had frequently been marked by "violence, intimidation and widespread fraud."

However, it urged the state poll watchdog Commission on Elections (Comelec) to do more to ensure the machines, which are to be used for the first time to count ballots and pool and transmit results from more than 350,000 precincts, are fraud-proof and have adequate backup.

"The perception, whether fair or not, is that the Comelec has not done so. When it concerns elections, perceptions can be as important as reality," it said.

This perception has "inhibited public confidence in the elections and generated anxiety about the automated election system."

Fifty million voters are set to go to the polls on May 10, when 17,000 posts from president down to municipal council seats will be contested.

The report said the Comelec has yet to reveal to candidates and voters what backup plan they have in place in the event the automated system fails.

"The biggest challenge and contribution that the Comelec can make is to communicate openly and frankly," Thomas Barry, NDI's deputy regional director for Asia, told a news conference.