Fire crews were called to the Co-operative Petrol Station on Wellworthy Road in Lymington, just a week after the station was first closed because of a gas leak.
A spokesperson for Hampshire Fire and Rescue Service said: For safety a 100m cordon was put in place once we verified there was a leak. Once the site was made safe, we handed over to security and police.
Last week an LPG leak was discovered in the line between the tank and dispenser.
The tank was isolated and around 50 litres of LPG was vented into the air, with large fans used to help disperse the gas. Since then, the site has remained closed.
A spokesperson for the Co-op said: The safety of customers and colleagues is our number one priority. The fire brigade attended to conduct some monitoring tests as part of our ongoing investigations.
"We expect the site will be closed for at least a further week and apologise for any inconvenience.