Coleman was unveiled as the successor to his former Wales team-mate Gary Speed at a press conference in Cardiff on Thursday, having left his role with Larissa last week, citing the Greek club's financial problems as the reason for his departure.
But within hours of the FAW confirming Coleman's appointment, with the 41-year-old being handed a contract through to the end of Wales' World Cup qualifying campaign, Larissa posted a statement on their website stating that the former Fulham manager remained under contract with them, and a Larissa spokesman told BBC Sport: "We have started legal proceedings...to claim compensation from the Welsh FA."
The spokesman added: "We are also prepared to take the matter to FIFA."
But Press Association Sport understands the FAW are confident that they and Coleman have been thorough and correct in all matters relating to his appointment, with Larissa's failure to pay Coleman and members of his staff due to their financial problems meaning they were in breach of his contract.
Coleman has previously said the club had not paid him and during his unveiling he claimed: "I left Larissa two points off the top of the league. I left them because financially they are in big trouble. Some of the staff had not been paid for six months, eight months, up to a year."
Coleman had taken charge of Larissa in May last year, and they were enjoying a successful season under his guidance.
A statement on Larissa's website read: "On January 8, 2012, Chris Coleman gave his last interview as head coach of Larissa, saying the causes of his departure were unrelated to the national team of his country; today, 11 days afterwards it has been announced officially that he will be the new national coach of Wales.
"Once it became known that Chris Coleman, who has a contract until next June, would be leaving, the club has been heavily criticised despite the president saying publicly he did everything to keep Coleman at the club.
"Instead of asking for an apology from all those who criticised us, we instead feel the need to apologise for our choice in appointing Chris Coleman."
Source: PA
Source: PA