The Public Transport Authority says it has no plans to suspend its gas bus fleet despite two vehicles catching fire in less than two months.
A Transperth bus driver ordered around 20 passengers to abandon the Number 99 bus in Bentley late yesterday afternoon when he noticed a warning light on the dashboard.
The driver turned off the gas valve but a short time later the back of the bus was engulfed in flames.
It is the second time in less than two months that a gas bus has caught fire.
"We're doing everything we can to address this," he said.
"We're looking into it to find out. But there's nothing we've found out yet that suggests that people have got anything to be concerned out.
"So I would urge people not to be too concerned."
The Transport Minister Troy Buswell says the PTA has adopted a comprehensive inspection policy in the wake of the fire.
"We're doing everything we can to make those buses safe and we'll continue to do that," he said.
"We need to work with the suppliers. We need to upgrade our inspection regime which we're doing. We need to look at beefing up the fire suppression system and we need to work with our bus drivers and their union.
"I think we all have a common interest to make sure those buses are as safe as they can, the drivers are confident driving them and people are confident hopping into them."
Mr Buswell says there are no plans to suspend the fleet's 500 gas buses and he will meet representatives of the bus drivers' union on Monday to discuss their concerns.