EU policies, particularly those of Italy and Malta, are to blame for the deaths of 721 people at sea in June and July, Amnesty International has claimed.

In a damning report released on Wednesday, the human rights group said European agreements with Libya as well as hostility in Rome and Valletta towards migrant rescue ships were having a devastating impact.

“Despite a reduction in the number of people crossing the Mediterranean in recent months, the number of deaths at sea has risen,” said Matteo de Bellis, a researcher for Amnesty.

“European policies have helped the Libyan coastguard to intercept people at sea, lowering the priorities of rescue operations and hindering vital rescue work carried out by NGOs. The recent increase in the number of deaths is not only a tragedy, but a shame.”

The agency said 1,111 people were reported dead or missing in the central Mediterranean between January and June.

About 560 were reported dead or missing in June, the same month Italy’s populist coalition government came to power with a pledge to crack down on sea crossings, and 157 in July.

The first major anti-migrant move by Matteo Salvini, the interior minister and leader of the far-right League, was to block the arrival of the Aquarius rescue ship, which had more than 600 people onboard, prompting an international outcry and forcing it to divert to Spain.

The vessel, which had been on its way to Sicily, was caught in a standoff between Italy and Malta after both countries refused to allow it to dock.

Amnesty's figures come from the International Organisation for Migration, an intergovernmental group associated with the UN, and the Italian Institute for Political Studies.

Amnesty said the recent surge in deaths along the perilous route between Libya and southern Europe “cannot be dismissed as an inescapable misfortune”.

Italy and Malta’s increasingly hostile treatment of search and rescue NGOs has also depleted the Mediterranean of vital rescue assets, with several being recently impounded, the agency added.

The rise in the number of deaths at sea coincides with the number of migrants kept in detention centres in Libya increasing from 4,400 in March to more than 10,000, Amnesty says, citing figures from DCIM, a branch of Libya's interior ministry.

This, Amnesty says, is due to European and Italian policies that allow Libya’s coastguard to rescue people and bring them back to the country, where aid agencies say they face severe torture and abuse.

“Despite this,” the report said, “Italy and the EU are bolstering their policy of supporting the Libyan coastguard to ensure it prevents departures and carries out interceptions of refugees and migrants on the high seas in order to pull them back to Libya.”