The departure of the master of a Fratelli d’Amico Armatori tanker from Peru during an oil spill investigation has sparked controversy as officials pursue a $4.5bn lawsuit targeting several companies over the January incident.

Peruvian prosecutors have requested the extradition of Captain Giacomo Pisani and chief officer Nitesh Kumar as part of a continuing investigation into a spill that took place when the 158,300-dwt Mare Doricum (built 2009) was unloading a cargo of crude at a Repsol refinery near Lima.

Though Peru has aimed most of its ire for the spill at Repsol, the nation’s attorney general’s office accused Pisani of leaving Peru on 9 March, a day after a hearing seeking a court order to prevent him from exiting the country.

But Fratelli d’Amico said on Wednesday that there was no legal impediment to the two officers leaving the country.

“They were both due to be repatriated upon completion of the discharge operation at La Pampilla, Peru, having completed six-month and four-month contracts respectively,” the shipowner said in a statement.

“Prior to their departure, Captain Pisani and the chief officer continuously offered their full cooperation to the authorities, attending all hearings where their presence was requested.”

Fratelli d’Amico also said that once the two seafarers ended their contracts, the company had no authority to force them to comply with any requests by authorities.

“Any decision or action is the sole responsibility of each crew member,” the company.

Lawsuit filed

The statement came as Peruvian authorities pursue a lawsuit against Spanish oil giant Repsol, its Peru refinery and Fratelli d’Amico over the January spill.

Vessel snapshot

Name: Mare Doricum

Type: Crude tanker

Size: 158,319 dwt

Built: 2009

Owner: Fratelli d’Amico

Flag: Italy

Classification society: Rina

P&I insurer: Standard Club

Source: Equasis

The National Institute for Protection of Competition and Intellectual Property, referred to by its Spanish acronym Indecopi, also named two units of Mapfre Insurance and maritime agent Transtotal.

Respol, which has blamed the spill on waves from a massive volcanic eruption in Tonga, has described the lawsuit as “unfounded”.

Fratelli d’Amico said on Wednesday that it no longer considers the Mare Doricum’s presence in Peru necessary.

Despite that, the company said it provided security in case claims arise, which led the harbour master to release the ship from seizure on 11 February. But the tanker remains at anchor off Callao, vessel tracking data shows.

Fratelli d’Amico said all evidence supplied to authorities has confirmed that the suezmax’s crew adhered to all onboard protocols, following the same instructions from local pilots and the terminal that had been used for 800 tankers before it.

The company also said that when a mooring line snapped during the operation, the Mare Doricum crew sought assistance from the Repsol terminal to replace it in an operation that the shipowner said should have taken 10 minutes but instead took more than an hour.

And Fratelli d’Amico reiterated that its crew stopped offloading operations as soon as oil was detected in the water.

The Italian company said an investigation by classification society RINA found that mechanical systems were in order.

Mapfre and Transtotal, a subsidiary of Ultramar, could not be immediately reached for comment for this story.