TUNIS (Reuters) - Tunisia’s Prime Minister Youssef Chahed sacked the energy minister, Khaled Kaddour, and four other senior figures linked to that ministry on Friday over corruption accusations, government officials said.

Chahed ordered an investigation and the merger of the ministries of energy and industry, an official source told Reuters. One of the officials denied any wrong doing, but there was no immediate comment from the minister or the others.

Government spokesman Iyad Dahmani said the sacked were accused of allowing a Tunisian investor to explore the Halk Manzel oilfield - one of the country’s most important sites - without having to go through a licensing round.

The deal over the oilfield near the coastal city of Monastir also came with unjustified tax privileges, Dahmani said.

Kaddour is the first minister targeted in a crackdown on corruption that Chahed launched last year. So far only mid-level officials have lost their jobs.

One of the other officials dismissed on Friday - Secretary of State for Energy, Hachem Hmidi - told Reuters he denied the accusations.

“My exit from the government helps me to devote myself to the case and prove that I am innocent of these malicious charges,” he said.

The other officials named by the official source were the director general of fuel, the head of the national oil company, ETAP, and the ministry’s director general of legal affairs.

Corruption was one of main catalysts of the 2011 revolt against autocrat Zine El-Abidine Ben Ali. Many Tunisians complain graft remains widespread despite a democratic transition since 2011 with free elections.

Last year, the government confiscated the property and froze bank accounts of about 20 prominent businessmen arrested on suspicion of corruption.

In July, parliament approved a law forcing senior officials to disclose assets - part of a fight against what it calls illicit enrichment.

Tunisia’s anti-corruption committee has said graft is still widespread in all business sectors and causes losses worth billions of dollars every year.

Chafik Jaraya, who maintains political contacts in Tunisia and Libya and helped finance the Nidaa Tounes ruling party during the last elections in 2014, was among those arrested last year.

He is in jail awaiting trial. His lawyer has said the charges are politically motivated.