Some 100,000 people took to the streets last Sunday in Bulgaria’s latest wave of protests against poverty and rising utility prices.
The protests forced the government to resign last month.
Two of the three protesters who have set themselves on fire in the last month have died.
More than 2,000 miners, railway workers and power engineers protested at the State Energy and Water Regulatory Commission on Tuesday.
They chanted “mafia”, “trash” and “we want bread and jobs”.
Talks on trying to include some protester and union representatives in a new government have broken down.