Argentina's president has joined calls for the search for missing Cardiff City footballer Emiliano Sala to resume.
Mauricio Macri told his foreign minister to issue formal requests to Britain and France, according to a statement from his office.
The search for the Argentine striker, 28, and pilot David Ibbotson, 59, was called off on Thursday.
The plane disappeared from radar as the pair flew over the English Channel on their way to Cardiff on Monday night.
In a statement, the president's office said: "President Mauricio Macri instructed foreign minister Jorge Faurie to make a formal request to the governments of Great Britain and France to ask them to maintain the search efforts."
Mr Faurie is expected to make the request to both nations' embassies.
Earlier, Sala's sister Romina said: "We are convinced Emiliano and the pilot are alive somewhere in the channel."
Speaking through an interpreter, Ms Sala added: "I'm still in shock. We know Emiliano and the pilot are still alive. We want to go and search for them.
"We're asking please don't stop with this effort. All together, we will find a way to restart the search to find Emiliano."
The Air Accidents Investigation Branch has begun an investigation which will look at "all operational aspects," including licensing and flight plans.
The Piper PA-46 Malibu disappeared over the English Channel with Cardiff City's new signing and Mr Ibbotson on board.
A "moment of silent reflection" for the pair will take place at the next round of Premier League fixtures on Tuesday and Wednesday.
Mr Ibbotson of Crowle, Lincolnshire, held a private pilot's licence and passed a medical exam as recently as November, according to Federal Aviation Administration records.
The Civil Aviation Authority said the aircraft was registered in the US, so fell under its regulations.
US law states private pilots cannot make a profit by carrying passengers.
Argentine striker Sala signed for the Bluebirds from Nantes on Saturday and was flying back to Wales from France when the plane disappeared from radar.
At 19:15 GMT, Mr Ibbotson made a request to descend before losing contact with Jersey air traffic control.
Guernsey's harbour master explained a "difficult" decision was made to call off the search on Thursday, saying the chances of survival were "extremely remote".
Captain David Barker acknowledged the family were "not content" with the decision, but was "absolutely confident" no more could have been done.
He insisted UK coastguard protocols were followed and hoped the families found some comfort in the incident remaining open, despite searches ceasing.
A petition launched in France to have the search resumed has gathered more than 67,000 signatures.
Sala's former club Nantes, along with many of its players, backed Ms Sala's calls, saying: "FC Nantes learned searches for the missing plane have been called off. These cannot stop."
Barcelona star Lionel Messi - a fellow Argentine - posted a message of support for his compatriot on Instagram.
Three planes and five helicopters racked up 80 hours combined flying time looking for the plane, working alongside two lifeboats and other passing ships.
Ms Sala said she held a meeting with investigators, but could not comment about it, and said the family were grateful for all the support they had received.
Cardiff City's owner Vincent Tan said: "Monday evening's news shook everyone at Cardiff City FC to the core.
"We also thank everyone involved with the search and rescue operation, and continue to pray for Emiliano, David Ibbotson and their families."
Chief executive Ken Choo praised Sala as a "humble man", adding: "He's willing to fight and join us [Cardiff City] and help us, so I view him as a hero."
He said the club would provide information to the family, but added: "With a missing plane, there is a lot of information to acquire - it could take up to six months to a year."
There were "alarm bells all around" the incident, aviation consultant Alastair Rosenchein told BBC Radio Wales' Good Morning Wales programme.
He said: "The one issue is whether a single-engine air craft should be flying at night, in winter, over water and with passengers. This is the real issue - it is a really bad combination."
He said despite only 1,400 of the planes being built, there was a "quite significant" number of deaths and injuries from flights involving them.