Cardiff City are at the centre of an unprecedented sporting dispute over the transfer fee for Emiliano Sala that has gone to FIFA and could end up in the High Court, then the Court of Arbitration of Sport in Switzerland.

It centres around who should pay for the Sala transfer, which would total £17million when you include a signing-on fee, bonuses and other payments.

Some pundits and football fans believe Cardiff should hand over the money to Nantes after announcing Sala as their player on January 19, two days before the fatal flight.

But it is far, far more complicated than that, with lawyers and insurance companies in Wales, England and France poring over the small print.

Here we try to shed as much light as possible on a highly complex matter that is testing the football authorities and barristers to the full...

WHEN CARDIFF ANNOUNCED SALA

The Bluebirds unveiled Sala as their player at 7pm on Saturday, January 19, two hours after Neil Warnock's men had been thrashed 3-0 at Newcastle. He would eclipse £11m Gary Medel as the club's record signing.

This is how we reported the story at the time

It is thought Cardiff's hierarchy fast-tracked the announcement to give the fans some cheer following an abject display up on Tyneside.

The announcement came just two days before the tragic flight on Monday, January 21, that that Sala and pilot David Ibbotson, who remains unaccounted for, were on.

Crucially, Cardiff stated the deal was subject to clearance from the authorities.

Due to the awful circumstances, that clearance did not happen and the lawyers have been looking at the various technicalities.

THE FOUR CRITERIA THAT NEED TO BE DELIVERED

For the Sala deal to have been valid, four criteria needed to be fulfilled.

We understand these came under Clause 2.4 of the transfer agreement struck between Cardiff and Nantes.

1. Register with the FA of Wales

As a Welsh club, the Bluebirds come under FAW jurisdiction for the signing of players, as opposed to the English FA, even though they play in the Premier League.

Cardiff captures have to be registered with the FAW under article five, paragraph one of FIFA Regulations on the 'Status and Transfer of Players before they are eligible to participate in organised football'.

It is understood Sala's documents were lodged by Cardiff with the FAW by the Monday morning - the day of the fateful flight from Nantes.

2. International Transfer Certificate

This is what the FAW would have provided once clearance was agreed between themselves, the Ligue de Football Professionnel (who run the game in France), Cardiff and Nantes.

Sala was in effect a Cardiff player, but needed the International Transfer Certificate before he could be registered to play in different competitions.

(Image: AFP/Getty Images)

It is understood the FAW had not confirmed the Sala transfer with Nantes because there were missing pieces of documentation. It is claimed the French authorities only confirmed with Nantes on Friday, January 25 - four days after the light aircraft carrying Sala plunged into the English Channel.

Hence, there is some confusion over the validity of the International Transfer Certificate.

3. Premier League registration

Even if the above had happened, Cardiff still required the official go-ahead from the Premier League for Sala to play. That was not given and forms a key plank of the whole dispute.

The loophole centres around Sala's personal terms.

4. Personal terms

For a transfer to become valid, player personal terms have to be concluded, and they weren't.

Sala, we understand, asked for his signing-on fee to be paid 100 per cent up front and had signed a contract, but the Premier League said it was invalid.

They wrote to Cardiff to say they didn't do business that way, pointing out it was custom and practice to pay in installments over the three-year duration of the contract.

Cardiff were told to renegotiate with Sala on those terms. Until that happened, he couldn't be registered to play in the Premier League.

As such, Sala was NOT eligible to play for the Bluebirds in their next game — away to Arsenal on Tuesday, January 29 — until that criteria was satisfied.

Of course, it could have been a simple formality for Cardiff to rearrange with Sala.

However, it is the Bluebirds' contention that Sala could have declined those terms and moved to a club abroad. He had just turned down a big-money move to China to agree to join the Bluebirds.

It is thought Cardiff's lawyers have examples of previous transfers which broke down at the 11th hour over this type of personal terms complication.

WHAT NANTES SAY

The French club have asked FIFA to intervene and the Bluebirds have been given until April 3 to give their side of the story.

Nantes' argument is that even if the paperwork was technically incomplete, there was an intent by Cardiff to register Sala.

THE LAWYERS — AND INSURANCE COMPANIES

The Bluebirds have employed Cardiff-based firm Capital Law to deal with the matter.

Their founder member Chris Nott, OBE, is a director of Cardiff Blues and has previously represented the Bluebirds in a dispute with former owner Sam Hammam.

Nantes also have legal representation and some of the dispute will hinge on whether the plane tragedy comes under French or English law.

The insurance companies for Cardiff and Nantes will each be looking into the case, but this is another highly complicated matter within the bigger picture.

Which insurance company becomes liable for the £17m fee - Cardiff's, Nantes', or is it public liability insurance via the owners of the plane?

Concerns raised over the lawfulness of the flight muddies the issue further and could potentially prohibit a payout.

The Piper Malibu aircraft was able to be flown by private pilots holding the appropriate licence, but it was not allowed to be used for commercial operations.

Cardiff were due to pay the Sala fee in three installments, but withheld the first £5m payment which was due on February 20. As soon as they commit to a payment, they in effect admit liability.

When players sign for Cardiff, they go onto a group cover. But the Bluebirds' insurers will want evidence Sala was definitively registered as a Cardiff City player to be insurable under their terms and conditions.

Meanwhile, high-profile London QC Michael Mansfield has also been brought on board by the Sala family to look after theirs and Emiliano's interests.

WILLIE MCKAY'S INVOLVEMENT AND THE DOOMED FLIGHT

Cardiff want to ascertain the exact tie-up between football agent Willie McKay and Nantes, plus his involvement on arranging the doomed flight for Sala.

McKay says he contacted David Henderson to arrange the flight - an experienced pilot who, McKay says, had flown him and many of his players throughout Europe on countless occasions. However, McKay insists he was not involved in selecting either the plane or the pilot.

Cardiff also want further details of why McKay told Sala he had planted stories about interest from other clubs "in order to create an interest around you".

The Bluebirds sent letters to Everton, West Ham and Crystal Palace to ascertain whether they had any interest in Sala and wonder if the fee could have risen unnecessarily.

Cardiff have a four-man committee who decide upon transfers, made up of manager Neil Warnock, owner Vincent Tan, chairman Mehmet Dalman and chief executive Ken Choo.

We believe one member of that panel refused to vote for the £15m deal because he was uncomfortable with it.

DIDN'T CARDIFF HAVE A DUTY OF CARE?

Yes, they did. But the Bluebirds will argue they offered Sala a British Airways flight to come back to the UK from France.

They feel the matter was taken out of their hands. Players take private flights on a regular basis.

It's unchartered territory, but Cardiff want the following three questions answered:

Who has liability for Sala being on a flight with a pilot who held a private pilot's licence which does not permit carrying passengers for reward? What was the condition of the plane? Why was it flying at night across the largest section of the English Channel?

(Image: SEBASTIEN SALOM GOMIS/AFP/Getty Images)

COULD FIFA DOCK CARDIFF POINTS?

This has been suggested, with one sports law expert claiming Cardiff could be punished if they don't pay.

But Cardiff have spoken to the Premier League about the matter and there is little indication this will happen and affect their relegation fight.

A COMPROMISE, SURELY?

Logic decrees that the two clubs will eventually come to an agreement of some sort, maybe the Bluebirds paying around half and Nantes writing off the rest?

But there seems no sign at this stage of Nantes playing ball.

Complicating matters further is the fact Sala's former club Bordeaux are entitled to 50 per cent of the fee. So that would be either half of £15m, or half of whatever compromise Cardiff and Nantes could conceivably strike.

ANY OTHER SOLUTION?

Yes, the case could go to the Court of Arbitration of Sport in Switzerland.

They provide mediation on sporting disputes and help parties settle matters in an amicable way.

But you can appeal, albeit on limited grounds, which would take up even more time.

(Image: Getty Images)

WILL CARDIFF PAY UP?

The Bluebirds have always said they will do "the right and proper thing". Thus, if the registration documents prove Sala was a Cardiff player, or FIFA rule in Nantes' favour, Cardiff will probably pay.

But they believe the evidence thus far indicates the opposite and Cardiff's hierarchy feel they have a duty of care to the football club to establish full disclosure of the facts.

There are a whole raft of questions still to be answered and a number of experts continue to look into the case for the Bluebirds.

There is also the option of Cardiff suing, pending upon the outcome of the final Air Accident Investigation report, which could well take up to 12 months to publish from the date of the tragic flight.

The only thing we can be clear about is that this will drag on and on for some time yet.