Two senior staff have left Brisbane City Council in the wake of a $60 million tech blowout.

The council's $122 million project to merge 13 systems into one by mid-2017 has been delayed by over a year, and will end up costing about 50 per cent more than originally budgeted.

“Two senior players have gone,” Mayor Graham Quirk told reporters this week.

“They made the decision after discussions with the CEO. There has been an agreement across the board.

“I don't believe there will be anymore [people leaving] at this time.”

The council wants to renegotiate its contract with Brisbane firm TechnologyOne, which claims that the scope of the original deal has expanded significantly.

“The delays are due to well-documented changes in project strategy requested by the BCC [Brisbane City Council],” TechnologyOne chief executive Adrian Di Marco said in a statement to the ASX.

“In the worst-case scenario of litigation, given the fact above, TechnologyOne remains confident of its legal and commercial position.”

TechnologyOne’s original contract was worth $50 million over a decade for development, configuration, implementation, interfaces and data migration.

A remaining $72 million of that contract went to costs associated with council staff and contractors.