Updated 8.10pm with Grech's reaction

Prime Minister Robert Abela insisted on Monday that he had not discussed the opposition leader’s tax affairs with tax chief Marvin Gaerty but had only handed him information that Bernard Grech had not paid his taxes for years.

Abela was replying to questions after Times of Malta reported that Gaerty’s phone contained a Pandora’s Box of sensitive information, including a conversation in which the prime minister refers to confidential information about Grech’s taxes. 

Gaerty is currently on police bail after he was questioned in connection with a conversation he had with Daphne Caruana Galizia murder suspect Yorgen Fenech in 2014.

Questions sent to the prime minister on Saturday were not answered, while Gaerty would not say whether the prime minister had asked him to divulge tax secrets on his political opponent.

The prime minister said he had received information "from within the Nationalist Party" that Grech had not paid his taxes "for years". 

He said he had done his duty in passing on the information to the tax chief, insisting that the real issue was not the procedure, but that Grech had not paid his taxes for years until he did so promptly because of the PN leadership campaign.

In a Facebook post, shadow justice minister Jason Azzopardi had asked whether the prime minister could deny that between July and September, he had illegally requested information about Grech from the tax commissioner. He also asked whether the prime minister could deny that there was evidence of this on Gaerty's phone. 

Abela took questions on Monday after he laid flowers on the memorial to Karin Grech, who was killed by a letter bomb addressed to her father at the height of the doctors’ strike 43 years ago.  

Opposition leader Bernard Grech in a reaction said the prime minister had confirmed that he had tried to influence the election of the leader of the Nationalist Party in what was tantamount to clear abuse of power. 

He challenged Abela to publish his own income tax and VAT returns and to declare whether he had ever discussed his own tax affairs with the tax commissioner.