The unauthorised clearance of a protected area of woodland was "horrific" local residents have said.
Eastleigh Borough Council said its enforcement officers were called to site clearance works at Scoreys Copse in Horton Heath on Saturday.
There were also reports of burning taking place on the one-acre site on Monday.
Local resident Sam Allen said trees were ripped up that had "stood for centuries".
The council said a number of trees protected by a Tree Preservation Orders were felled during the work.
The land also has an oil pipeline running underneath it.
A statement said: "Council enforcement officers attended the site as a matter of urgency and formally requested the works to immediately stop."
It said its legal team was working on a "appropriate course of enforcement action".
Mr Allen said a "huge industrial digger" had cleared the site and work continued after the council had attended.
"I awoke to hear the unmistakeable sound of trees splintering and was horrified to see this digger just ripping out trees that have stood for centuries."
Wildlife protection officers also attended and Hampshire Constabulary said they were monitoring the situation and liaising with the council.