The political rallies are taking a toll on vegetable farmers, who are finding it difficult to transport their produce to Bangkok.
Somchart Sroythong, director-general of the Internal Trade Department, inspects vegetables at Pathom Mongkol fresh market in Nakhon Pathom.
The farmers, notably in the western and northern provinces, are instead dumping their supply at Srimuang wholesale market in Nakhon Pathom province at deep price cuts.
Napintorn Srisunpang, the president of Agro Commerce Group, which runs Srimuang Central Market, said most farmers and small suppliers are reluctant to go to Bangkok for fear of traffic congestion caused by the mass rallies.
Srimuang is one of the three main markets for fruits and vegetables in the central region.
The other two are Si Mum Muang and Talad Thai, both in Pathum Thani province.
The three markets supply a combined 15,000 tonnes of fruits and vegetables per day.
Total fruit and vegetable supplies are 20,000 tonnes a day.
However, Mr Napintorn said in the wake of the mass rallies in Bangkok, supply to Srimuang Central Market alone has surged by 1,000 tonnes a day.
Most farmers and suppliers are willing to sell to Srimuang even though it means 25-30% less revenue.
Mr Napintorn said conversely, prices of fruits and vegetables in Bangkok may increase due to lower supply.
Sukiet Kittitammachote, senior corporate affairs manager at Tesco Lotus, said the company has not yet seen any irregularities in food and consumer product prices or hoarding in Bangkok. Sales at all its Bangkok branches remain at normal levels, he said.
But Mr Sukiet admitted consumer spending could be affected if the mass rallies last for another month.
Somchart Sroythong, director-general of the Internal Trade Department, insisted fruit and vegetable supplies are sufficient to meet demand.
Prices also remain unchanged from a year before, while those of some vegetables have fallen due to higher supply by the cool weather, he said.
Mr Somchart said his department is closely monitoring product price movements and has prepared measures to curb shortages or profiteering by vendors.
Officers are inspecting the prices of food and products in fresh markets in Bangkok and major distribution centres.