Support from Ciudadanos (Cs) for the minority Partido Popular (PP) control on Malaga city council collapsed this week because of disagreements over the mayor's handling of a long-running town-planning dispute.
On Monday, Juan Cassá, leader of Cs , withdrew support for mayor Francisco de la Torre after he refused to sack two PP councillors who are being investigated over political interference.
The case centres on 115 supposed town planning violations recorded in 2013 by council officials at the Villas del Arenal housing area, on the city's outskirts.
Councillor for Town Planning, Francisco Pomares, and councillor for the local area, Teresa Porras, are to be quizzed over allegations that they tried to interfere with council officers' work in order to reduce or remove fines. The chief planning inspector at the council was removed from her post at the time.
The mayor and the councillors say they have acted correctly at all times and that the fines for mild offences, such as building barbecue areas, were disproportionate.
Porras claimed this week that the break was part of electioneering by Cs ahead of local polls in May.