More than a dozen caravans have parked on Milton Common, causing anger amongst both politicians and residents who live nearby.
Earlier this week, landowner Portsmouth City Council sent officials from the anti-social behaviour unit to deal with the group, which has also set up kennels and chicken coops.
When this failed to move the travellers along, the council took the next legal steps to evict the group.
A council spokesperson said: ‘After carrying out welfare checks, we served notices to quit on two groups of travellers earlier this week, as the landowner.
‘They haven't left, so we've begun legal proceedings to evict them.
‘We expect to get a court hearing early next week.’
Other vehicles, including quad bikes, are parked on the common, and rubbish has been left strewn across the area.