Italy has detained a civilian rescue ship operating in the Mediterranean after the crew ignored orders to dock in a port over 1,000 kilometres away following a rescue mission, German organization Sea-Watch said on Monday.

Italian authorities imposed a 20-day detention order and a €10,000 ($11,500) fine on the Sea-Watch 5, the group said in a statement.

Sea-Watch is one of several civilian organizations operating in the Mediterranean to assist migrants as they attempt to reach Europe in often unseaworthy vessels.

On March 15, the Sea-Watch 5 took 93 people on board after finding them in distress in international waters, according to the group.

Italian authorities then ordered the crew "to proceed to a designated port more than 1,100 kilometers away," Sea-Watch said.

A few days later, the captain decided to head to a much closer port in Sicily instead "to safeguard the fundamental right to life."

Sea-Watch condemned the detention as "a predictable measure designed to sabotage civilian sea rescue operations."

The Italian government under far-right Prime Minister Giorgia Meloni has taken a tough a stance against migrants, especially those arriving from the Middle East and North Africa by boat.

A decree passed three years ago requires civilian rescue vessels to immediately head to a designated port following a rescue operation.

Rescue groups operating in the Mediterranean, including Sea-Watch, have repeatedly accused the government of attempting to systematically obstruct their work by assigning ports that require long travel times or detaining their vessels.