Middlesbrough were today conducting an inquiry into why several of their players failed to return for pre-season training.
It is understood Tuncay Sanli, Mido and Afonso Alves were not among the men who reported back to the club's Rockliffe Park training headquarters yesterday.
The Turkey international is believed to have been given an extended break after his international commitments at the end of the last campaign, along with keeper Brad Jones and England Under-21 stars Adam Johnson and Andrew Taylor.
But reports have suggested that controversial Egypt international Mido and record signing Alves were also missing.
The club was not commenting on specific players today, but a spokesman said: "The players returned to training yesterday. A number of them were missing, some with permission and others without.
"The matter will be dealt with internally."
Mido spent the second half of last season on loan at Wigan and may well have clinched a permanent move had manager Steve Bruce not made the switch to Sunderland.
He is unlikely to be part of manager Gareth Southgate's long-term plans after a mixed spell at the Riverside Stadium since his £6m arrival from Tottenham in August 2007.
However, Alves, who cost the club £12.7m in January 2008, still has three years remaining on his contract and it would take a sizeable bid before the Teessiders could even consider doing business, something which is perhaps unlikely with his form to date disappointing.Reuse content