A Perth man has surprised strangers with a simple but powerful act of kindness, paying for their fuel during a late-night stop as many Australians grapple with rising petrol costs.

Monty Van Der Berg, 34, had stopped to fill up at a BP petrol station in Currambine, Perth, about 10.30pm on Monday when he noticed another driver had only added $7 worth of fuel.

Seeing an opportunity to help, he offered to cover the cost for others at the station.

“(Another driver) pulled in right next to me, so I thought here’s my chance. I told her to fill up all the way,” he told 7NEWS.com.au.

Inside the kiosk, he extended the gesture to another customer, prompting an emotional response.

“I am the crying lady. I had just finished a heavy shift and have been working lots of double shifts in both my jobs. I was exhausted,” the worker posted online.

“I was just overwhelmed by the gesture. I hope this gets back to him. I couldn’t be more thankful.”

Van Der Berg said he told her “it’s not a big deal”.

“Then a guy was coming in and I told the teller, ‘I will get his (petrol) as well’,” he said.

“It’s just nice to be able to do things like that.”

One of the recipients, Rachael Greville, said she had planned to spend just $20.

“I had my petrol light on and was only going to put $20 in,” the single mother of two said.

“He said ‘I hope you’re filling up because I’m going to pay for it’,” she said.

“I was gobsmacked, I couldn’t believe it. I thought I was delirious.”

Greville, who is working three jobs, said the gesture meant she now had enough fuel for the week.

“I was in shock. It was so nice to see other people light up. It was such a nice moment,” she said.

In total, Van Der Berg spent about $480 helping strangers that night.

He said the gesture was shaped by his own past experiences, having previously lived week-to-week before building his construction business.

“It’s just nice to be able to do things like that,” he said.

“That’s my one thing — every time I fill up I like to pay for at least one other person.”

Van Der Berg said he usually prefers to help quietly without drawing attention.

“I didn’t do it for recognition. It was nice. (Monday) made me think about things — I want to do more,” he said.

Greville said she hopes to thank him in person and return the favour, and that if they meet again, it will be her shout.

Images: 7News