With exhausts that belch out dark clouds of fumes, drivers who arrogantly break road rules and sardine-can-like interiors, "jeepney" mini-buses are an unlikely source of pride in the Philippines.

The iconic vehicles with their flamboyant paint designs are much loved as a symbol of national ingenuity because Filipinos created them from surplus US military jeeps after American forces left at the end of World War II.

However, six decades later, they are also becoming known as environmental vandals because their huge diesel-powered motors are one of the major contributors to air pollution and ensuing health problems in Philippine cities.

"Because the old jeepneys are all diesel fed and so inefficient, they produce a lot of pollution," said Red Constantino, director of the Institute for Climate and Sustainable Cities, a Manila-based non-government organisation.

Constantino, along with a small collection of politicians, business groups and other NGOs, has embarked on a campaign to turn the Philippines' main form of public transport green by replacing them with so-called "e-jeepneys".

The e-jeepneys look like little more than glorified golf carts, but they are an emissions-free form of transport powered by electricity that carry a dozen people each.

After charging for between six and eight hours, the e-jeepneys can travel about 70 kilometres (45 miles) at speeds of up to 60 kilometres an hour, according to their manufacturer, Philippine Utility Vehicle.

Makati, Metro Manila's financial district and arguably its most orderly city, introduced the e-jeepneys on two so-called "green routes" late last year.

"Because of the e-jeepney we were able to reduce smoke-belching problems... and that was able to give an answer to our problems of air pollution," Makati mayor Jejomar Binay told AFP on board one of the mini-buses recently.

With only 15 servicing Makati, compared with 60,000 licensed traditional jeepneys across all of Metro Manila, Binay may have been overstating the environmental benefits in his enthusiasm for the project.

Nevertheless, Constantino, a former climate change campaigner for Greenpeace, said the Makati project was crucial in offering a showcase for the future.

"It's very important to have solutions on the ground to show people that these types of things are viable," he said.

"Our goal is to eventually replace all public utility vehicles with appropriate electric ones."

Constantino said momentum was starting to build, with a third green route to be opened in Makati next month and other city governments in Metro Manila placing orders to buy e-jeepneys.

Meanwhile, Puerto Princesa, the capital of Palawan island in the southwest of the archipelago, is developing as a second flagship city for the planned e-transport revolution.

Puerto Princesa authorities are aiming to introduce an e-jeepney fleet, but their major ambition is to replace the city's 4,000 gasoline-powered tricycles with electric "e-trikes", Constantino said.

A big next step for Puerto Princesa and Makati is to build biogas plants to power the e-vehicles with organic waste from local markets and households, rather than using fossil-fuel derived electricity as is currently the case.

Puerto Princesa began construction of a one-megawatt biogas plant, costing 2.4 million dollars, in February to fuel its electric public transport fleet.

Tropical storm Ketsana, which submerged vast parts of Manila in October last year, delayed a similar project for Makati but Constantino said that would also soon get underway.

Amid the hype for the e-jeepneys - they have won a plethora of positive reports in the local media - traditional jeepney drivers remain skeptical.

"We are not against e-jeeps, we know they are for our common good but they only work in Makati where roads are smooth," said Federation of Jeepney Operators and Drivers Association of the Philippines president Zeny Maranan.

"I also want to see how long e-jeeps will last for. And I see maintenance as a problem... our current jeepneys have durable chassis and bodies that can withstand collisions. How about an e-jeep, how sturdy is it?"

Nevertheless, Maranan conceded that old jeepneys - with powerful engines and bodies originally designed for battle rather than city traffic - had serious environmental flaws.

"It is difficult to deny the fact about the black smoke emissions and poor performances of our jeepneys," she said.

Maranan said the jeepney industry was exploring ways of switching the vehicles' fuel source from diesel to natural gas.

However few conversions have taken place and Maranan said a green revolution would not happen without massive state funding.

"The government should take the initiative to save our environment. If it will provide the budget, we are willing to take part and have the e-jeep system implemented," she said.

Constantino and the others involved in the e-jeepney are refusing to wait for such an unlikely scenario to occur.

"We are trying to make the solutions of tomorrow available today," he said.