West Ham will continue to offer Diafra Sakho the best possible treatment to help the Senegal striker recover fully from his back problem.
Sakho has impressed for the Irons following his £3.5million summer move from Metz, scoring eight Barclays Premier League goals as the Upton Park club broke into the top four ahead of Christmas.
However, the 25-year-old has also been troubled by a back injury, which saw him sidelined in November and forced him to pull out of Senegal's international against Botswana.
Subsequently Sakho has since suffered a flare up of the issue which saw him substituted against West Brom on New Year's Day, which also meant he was not able to join Senegal in Dakar for their training camp ahead of the African Nations Cup and so will miss the tournament in Equatorial Guinea.
Senegal have been left less than impressed by the situation, with president Augustin Senghor insisting the federation will insist on the enforcement of FIFA regulations over injured players who have been called up for international duty, meaning Sakho could not play again for the Hammers even if he was fit for the duration of the tournament, which runs until February 8.
Press Association Sport, however, understands West Ham had two independent assessments, the latest of which advised against the player making any long-distance flight, as it could worsen his condition.
The Senegal federation were informed of this, with their own specialists invited to examine Sakho if they required.
Sakho will now remain in London to continue his rehabilitation, although no time frame has yet been set for his recovery.
Speaking ahead of the FA Cup tie at Everton on Tuesday night, Irons boss Sam Allardyce had stressed the club would take due care.
He said: ''Our major concern is making sure he is fit whenever he is fit.
"I just hope it is not going to be too long and is nothing more serious than last time, which was an impingement on the nerve, because that was serious enough."
Senegal federation president Senghor is adamant the player should not be available to West Ham if he could not play for the national team.
He said in a statement: "We will go to FIFA and the English FA to assert our rights and the regulations will apply, so that Diafra (Sakho) will not play for the time specified."
West Ham, meanwhile, hope to have Andy Carroll fit from a foot injury for Saturday's game at Swansea after the forward missed the FA Cup tie - which ended 1-1 with a late equaliser for Everton - because of a foot injury.
Midfielder Alex Song will also be available following his international retirement from Cameroon.
West Ham have, meanwhile, confirmed arrangements for season ticket renewals, the last at the Boleyn Ground before the east London club are scheduled to move to the Olympic Stadium.
With a high demand expected, supporters are being asked to pay either the full amount or a £75 deposit that will be refunded off the final cost for the 2015-16 campaign, which must be paid by an early deadline of April 17.
Following several years of a price freeze, the club confirmed there will be an increase of around five per cent, but not for junior tickets.
Joint-chairmen David Sullivan and David Gold said in a statement: "It is clear that our final year at the Boleyn Ground and our first year at the new (Olympic) Stadium will be two seasons that no West Ham fan will want to miss.
"It is in response to that demand - and the pressures of managing it - that we are beginning next season's renewals and sales process earlier than normal."
Vice-chairman Karren Brady believes West Ham now has a solid base to move forwards.
"Since 2010, our commitment to the fans has been to restore the club's long-term financial health, while at the same time investing substantially in improving the playing squad," she added on the club's official website.
"The nine signings we made last summer have all made a big impact and we are planning significant further investment in the playing staff this summer.
"We are also improving the financial situation at the club and are on course to meet our target of being clear of external debt by the time we move to our stunning new home on Queen Elizabeth Olympic Park."