Uber will hit customers with a second price hike in less than a month as it introduces a fuel surcharge on all its cars except electric vehicles.

The rideshare company raised prices six per cent in March and will add an extra five cents per kilometre from Wednesday until June 8.

Uber Australia managing director Emma Foley announced the news in a joint statement with the Transport Workers' Union (TWU) of Australia.  

'Uber and the TWU have been working closely together to address rising fuel costs for drivers,' she said.

'Following constructive discussions, Uber will introduce a temporary fuel surcharge to provide driver partners temporary relief in response to the current fuel crisis.

'This measure builds on the national fare update Uber introduced in March, which increased drivers' earnings across Australia, and reflects Uber's continued focus on improving driver earnings.'

With Uber drivers spending a lot more on fuel than they normally would due to the Middle East conflict, TWU of Australia national secretary Michael Kaine said the surcharge would help ease their struggles. 

'What we are seeing is rideshare drivers are in the same boat as anybody else working in transport,' he said. 

'They are spending around $40 to $50 extra per go when they are filling up.

'We hope that this surcharge will really make a big difference to them.'

Uber isn't the only service introducing the surcharge, with Didi also in the same boat, and Mr Kaine said he believed customers would be understanding.  

'Customers are very much aware of the increasing fuel costs as they will be affected by it in their everyday lives too,' he said.

'They have grown used to the convenience of being able to log into an app and a driver appear as if by magic - I think they will understand the pressures drivers are facing so will want to see them properly remunerated.

'If they have to pay a little bit more to keep that convenience, I think they will be understanding of why.'

Didi announced its additional charge a month ago and many of its drivers were happy with the change.  

'Didi's addition of its five-cent-per-kilometre fuel surcharge was certainly well received among drivers,' a Didi spokesman said.

'Following this, Didi also increased its minimum fare pricing in several major markets,' he said.

'Didi will continue to monitor its fare pricing and fuel surcharge as this crisis continues, making changes where necessary to best support our driver community.'

Meanwhile, the pressure of the global oil crisis continues to mount, with Australia indicating it will only help reopen the Strait of Hormuz if US President Donald Trump establishes a permanent ceasefire with Iran.

Defence Minister Richard Marles said the country would not commit naval forces while conditions remain unstable after the United States launched a naval blockade of Iranian ports overnight.