A junior Portuguese cabinet minister resigned on Thursday, becoming the first head to roll in a growing scandal over perceived nepotism within the Socialist ruling circle.

Deputy environment minister Carlos Martins stepped down the day after the cousin he hired as the deputy head of his cabinet, Armindo dos Santos Alves, himself resigned.

“I have always acted in good faith… but I think this affair could hurt the government,” Martins said.

Dubbed “|Familygate” in the Portuguese press, the scandal has arisen ahead of general elections in October, putting pressure on Prime Minister Antonio Costa.

During a parliamentary debate on Thursday, Costa called on deputies to “hold a serious debate to define the criteria of links considered admissable or not, which would apply to this and future governments”.

The current Portuguese government includes a couple and a father and daughter.

But the nepotism row blew up last month after media reports uncovered several more family ties in ministerial offices. (AFP)