The government has warned of possible attacks by armed groups over the election peroid, including attacks by fighters from New People's Army which, it authorities say, could launch attacks in 14 provinces across the country.
Oscar Calderon, the Philippine's national police chief director general, said he had ordered police commanders nationwide to take steps to pre-empt "the hostile plan of the communist terrorists".
The elections are for 12 out of 24 senators and all 236 members of the House of Representatives.
Over 17,000 local officials, including governors and mayors will also be elected. Vote counting is done by hand, so final results will not be expected for weeks.
Arroyo's presidency, though, is not at stake, although analysts have said the result could have a bearing on the opposition's efforts to unseat the president over allegations she cheated to win the May 2004 ballot, allegations she denies.
But opinion polls suggest that no major shifts are likely. The economy in what is one of Asia's poorest countries has been rallying, with the stock market is up 12 per cent this year and the peso at its strongest level against the US dollar since October 2000.
Campaign death toll
|The three-month campaign season |
has drawn to an end [AFP]
The deaths of hundreds of activists and supporters of opposition parties, killed since Arroyo came to power in 2001 with many alleged to have been victims of extrajudicial killings by the military, have led to greater international scrutiny of the country's elections.
Police have put the official death toll from the three-month campaign period at 113.
Military units have been drafted in to transport ballot boxes and escort foreign observers to outlying areas of the archipelago.
Aside from foreign observers accredited by the government, an independent team of 25 from 10 countries said they would monitor 13 areas that have been hit by violence and allegations of fraud.
The team is composed of journalists, academics and others from countries including Japan, Britain, Australia, South Korea and the US.
But many local election officials in isolated towns said on Sunday that they were still waiting for election materials, including indelible ink to mark voters and prevent multiple attempts to cast ballots.
The Philippines has 45 million registered voters, including a half-million of the 7.5 million Filipinos who live and work abroad.
The decision to start allowing them to vote in 2004 reflects the economic clout they represent, with the remittances that they send home providing the country's largest source of foreign currency.