The talented midfielder was injured before Barcelona's Champions League final against Manchester United but managed to play in the Catalans' 2-0 victory in Rome.

He consequently aggravated the complaint to miss out on the chance of playing with European champions Spain in this month's Confederations Cup.

"He has an injury which has a very high chance of suffering a relapse," Spain doctor Oscar Celada said on Friday.

"We have to look out for Andres' health and not expose him to a relapse.

"The recovery period is long, between six and eight weeks. He is crushed to see that the injury is worse than what he could have thought at the beginning."

Reports said Valencia midfielder Pablo Hernandez will replace Iniesta in Spain's squad.

Iniesta has been in sparkling form this season, putting in a series of impressive displays to help Barcelona win the treble (the Primera Liga, Copa del Rey and the Champions League).

Spain will play in Group A of the Confederations Cup that also includes hosts South Africa, New Zealand and Iraq.