Andres Iniesta has reportedly paid back extra tax owed in Japan over failure to declare part of his income, but claimed that he had also declared the earnings in Spain.

Spanish World Cup winner Iniesta, who spent five years with Japan's Vissel Kobe until 2023, was found to have failed to declare approximately 860 million yen ($5.7 million) in income for 2018, according to public broadcaster NHK and other media.

Foreign players in Japan are classified as either residents or non-residents for tax purposes.

If their contract is for less than one year and they are not accompanied by family members, they are classified as non-residents and pay less tax than residents, the reports said, citing the National Tax Agency.

The Osaka regional tax bureau judged that during 2018 Iniesta was a resident as he lived with his family members on a multi-year contract.

He was issued with an additional tax demand of approximately 580 million yen as a result.

"In fiscal 2018, I reported my income from all of the world to taxation authorities in Spain," Iniesta said in a statement issued through his management company, cited by NHK and other media.

"The Japanese taxation authorities began an investigation with focus on my residence status under tax rules, and concluded that I was a resident (in Japan) during part of 2018," he said.

Iniesta has paid back the additional tax demanded, the statement said.

"Therefore, the income during the period is under double taxation," he said, adding that he has demanded excess tax payment be returned based on the two country's agreement on double taxation.

The management company could not immediately be reached to confirm the reports.

The Osaka regional taxation bureau declined to comment when contacted by AFP.