Greek Prime Minister Alexis Tsipras on Monday defended a controversial arms sale to Saudi Arabia which Amnesty International said should be scrapped over Riyadh's involvement in fighting in Yemen, AFP reported.

Tsipras said there was nothing improper in the deal, which opposition parties said was poorly handled and whose fate is currently unclear.

The PM, whose Syriza party has a strong pacifist background, was specifically asked if the deal would be abandoned. He said it was a "beneficial agreement for the Greek state."

He called the attacks "a fabrication designed to disorient public opinion," adding that the main opposition New Democracy party should "apologise" to the defence ministry.

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

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