The Philippines is to roll out 100,000 electric tricycles in an effort to replace the petrol-powered ones that currently ply its cities, one of the project's financiers said Tuesday.

The "e-trikes" would provide an alternative to the gas-guzzling, smoke-belching motorised tricycles that now ferry Manila residents through narrow streets not served by buses, the Asian Development Bank (ADB) said.

ADB energy specialist Sohail Hasnie said the lender hoped the e-trikes would eventually replace some of the estimated 3.5 million gas-powered motorcycles and tricycles already in use in the country.

"It will not stop at e-trike. It will expand horizontally to other transports like buses... and once that happens, nationwide, the country's consumption of oil will come down," he said in a video message.

The $500 million project received the green-light Tuesday but a launch date for the vehicles has not yet been set.

The e-trikes, powered by an electric motor with rechargeable lithium-ion batteries, cost only $1.20 for a daily charge compared to the $6-8 in fuel a normal tricycle burns every day, the ADB said

There has been generally favourable reaction to a pilot project of 20 e-trikes that have been in service in one Manila district since last year, the bank said.

The ADB is lending the Philippines $300 million to acquire the vehicles.

The project will also get an $105 million in a soft loan and grant from the United Nations' Clean Technology Fund, which is administered by the ADB, the bank said. The Philippine government will provide $99 million.

The loans will also put up five solar charging stations so the e-trikes can be powered up without drawing on the electrical grid, the ADB said.

Other countries have also expressed interest in the e-trikes, said Hasnie.

The Philippines hopes to eventually become a centre for manufacturing these vehicles, he added.