The Ugandan parliament has vowed to block any more deals with oil exploration companies amidst charges that government ministers received bribes totaling in the tens of millions of dollars.

Gerald Karuhanga, an MP, told parliament on Monday that the London-based oil and gas exploration firm Tullow Oil paid bribes to top Ugandan officials in order gain to influence.

Karuhanga specifically named Prime Minister Amama Mbabazi, Foreign Minister Sam Kutesa and former Energy Minister Hilary Onek as having received bribes.

Onek, who was accused of receiving about $23-million, denied the accusation.

I am thoroughly hurt by these lies because if such an account really exists I deserve all the punishment on Earth, Onek told MPs.

Kutesa himself accused Karuhanga of abusing his parliamentary privilege by making false allegations

Is he in order to make defamatory statements against me which are false and well-knowing that he cannot repeat them outside this chamber?, Kutesa asked.

Also, in response to the charges, Tullow Oil’s chief executive Aidan Heavey, wrote in a letter to MPs: These accusations are demonstrably false and appear to be founded on misunderstandings about how the global oil and gas industry works. Tullow would welcome the opportunity to appear at an appropriate forum in parliament to refute these serious allegations and to explain, with other representatives from the industry, how the industry in which we are proud to work operates.

A correspondent for BBC in Kampala, Uganda, Joshua Mmali, said the decision is a huge setback for the country’s president Yoweri Museveni, who has been in power for a quarter-century.

The vote in parliament suggested MPs of the ruling party strongly supported the suspension of oil deals, meaning Museveni’s power may be slipping.

Mmali also indicated that MPs are seeking increased transparency with respect to Tullow’s deals with government figures.

Tullow currently operates three oil properties in Uganda’s Lake Albertine Rift.

Significant oil reserves were only discovered in 2006, suggesting Uganda could one day become a dominant petroleum producer in Africa.

Museveni was re-elected in February under a cloud of fraud allegations. He has also faced rising dissent among the public burdened by spiking commodity prices.