Businesses at Battlefield in Shrewsbury say they are regularly having to call police because of aggressive behaviour.
The situation escalated at the weekend when shops had to close early after staff received threats and stock was stolen.
The franchisee of Subway today spoke out about ongoing issues with some members of the travelling community, who often park near the shop.
Harry Blugher has called on Shropshire Council, which owns a car park nearby, to act to protect businesses.
Traders at the Sunday Market on the council-owned land had to pack up early after customers and stallholders were intimidated.
And Mr Blugher today said the travellers were threatening his staff, using the toilet as a wash room, and helping themselves to goods.
They also defecated on the pavement outside the shop once the doors were closed.
He said: “On Saturday my staff were threatened. They were told that if they called the police they would be in big trouble.
"We had the staff locked in and I had to come from home and get them out.
"They were very worried about coming into work. The staff were very shaken.
“On Saturday we kept them happy and let them use the toilets and then they came in and helped themselves to everything.
“The police got them to move and they just went on to the council-owned car park.
"They then left faeces outside the shop which I had to clean.”
Mr Blugher called on the council to take responsibility, adding: "If we get an issue like this it goes on for weeks and weeks before the council get it sorted. This problem has been ongoing for the past year.
"Five or six new caravans turned up yesterday, but they are peaceful."
The Featherbed pub also had to close at the weekend.
Relief manager Steve Mooney said: “We had children coming in and swearing at the staff and then the police were called.
“They came in and used the toilets like a wet room.
"A lot of the customers were understanding as we had to close early at 9pm.
"On Sunday morning there were about six police cars and a riot van called when there were problems at the market."
Safer Neighbourhood Inspector Ed Hancox said: "We are aware there were concerns over the weekend around a group of young people from the travelling community in Shrewsbury. These issues have since been resolved.
"The Safer Neighbourhood Team is committed to listening to the concerns of the local community and, in partnership with other agencies, looking at longer term to solutions to address their concerns and we would always urge people to get in contact to discuss these."
Shropshire Council said this morning that the problem group had left and the authority was taking the safety of residents and businesses seriously.
Steve Charmley, Shropshire Council cabinet member for corporate and commercial support, said: “Shropshire Council takes seriously the safety and prosperity of residents and businesses alike and the main group that were causing the problems have now vacated site.
“There are four caravans currently on the site but this is a single family unit who are well known to the liaison team and generally cause no issues. We have however served notice on the group which expires today at 3pm.”