Coleman, who was unveiled as the new Wales manager earlier on Thursday, took over at second division Larissa in May 2011 on a one-year contract but left on January 8, citing personal reasons and the club's financial problems as the reasons for his departure.
The club released a statement reacting to the news of his appointment and a spokesman said the 41-year-old Coleman had not signed a contract termination agreement.
"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," Larissa said.
"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."
A spokesman confirmed that Coleman was still under contract.
"We have started legal proceedings in order to claim compensation from the Welsh FA," he said. "We are also prepared to take the matter to FIFA."
Coleman replaced former Wales manager Gary Speed who was found dead at his home in November in an apparent suicide.
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