The Greek government has come under fire over a planned arms sale to Saudi Arabia that fell through amid accusations of incompetence against the defence minister, a key ally of Prime Minister Alexis Tsipras.

Opposition lawmakers say the botched deal for surplus military stock cost Greece 66 million euros ($78 million), while ruling party officials have questioned the sale of munitions to Saudi Arabia owing to its involvement in the Yemen conflict.

"Perhaps it's better that this deal was not concluded," Nikos Xydakis, a former junior foreign minister, told Skai TV on Friday.

The previous day one of Tsipras' top ministers and two other prominent lawmakers also expressed unease.

"Obviously, every country has a right to exploit its surplus munitions, but we need to be much more careful," Interior Minister Panos Skourletis told state TV ERT.

"A country of Greece's size (cannot) sell weapons without caring how it will be used," he said.

There are fears that the missiles could have been used in Saudi Arabia's fight against rebels in Yemen.

More than 8,750 people have been killed in the conflict and the country also faces a deadly cholera epidemic and millions stand at the brink of official famine.

Tsipras, whose coalition government depends on the nationalist ANEL party headed by defence minister Panos Kammenos, says the accusations are "baseless" and plans to address the issue in parliament on Monday.

Kammenos' office has released a document showing that the Greek defence ministry in June had agreed to sell 300,000 tank shells at a cost of 66 million euros to a Greek contractor claiming to represent Saudi Arabia.

But on the day the deal was signed, Greece's Riyadh embassy wired to say that the Saudi military had no knowledge of the Greek contractor's activities.

The opposition has also accused Kammenos of trying to bury the issue by transferring the officer who oversaw the attempted sale.

An opposition lawmaker investigating the case has also been threatened with prosecution after submitting to parliament documents which the government says are covered by state secrecy laws.

The opposition says the government's refusal to shed light on what was supposed to be a legal bilateral deal is suspect.

"What is the government trying to hide? Why are lawmakers unable to access documents pertaining to the sale?" New Democracy spokeswoman Maria Spyraki said Friday.

Source: AFP