MoneySavingExpert says Virgin has refused to tell them exactly which tariffs are affected, but all those hit by the hike should be receiving official notifications soon.
The rise will come into force from April.
In a statement, Virgin said: “We’re updating some of our older mobile plans so that our customers can continue to enjoy the best of our services. As always, any changes made will be communicated to our customers in a clear and timely way.”
The news of this rise comes as some other providers are also putting up prices.
Some EE, BT and Sky users are all being warned that they face higher costs starting from next month.