Virgin Media has been carrying out speed tests over its ultra-fast cable network, amid rumours of a 300Mb launch later this year.
ISPreview.co.uk has raised the possibility of another double-speed boost for Virgin Media customers, who have previously benefited from infrastructure upgrades at no extra cost.
The news provider said a "growing number" of customers have reported unusually high download speeds in the last few weeks.
It said this lends additional support to the widely rumoured introduction of a new 300Mb top tier for the firm's broadband customers.
At present, the maximum advertised broadband speeds for Virgin Media fixed-line subscribers are up to 152Mb.
In response to reports of enhanced broadband services, a Virgin Media Community Support Agent said the operator is "always trialling new faster speeds".
"This temporary speed increase is free of charge," the representative stated.
"We will be returning your speed to the original tier of service when the trial ends but in the meantime please enjoy the free temporary speed increase on us."