The Spurs skipper has been included in the latest England squad despite suffering with a long-standing knee problem.
The niggling injury means King is unable to train on a regular basis, while he he cannot play more than one game a week.
A previous cartilage operation means his right knee swells up markedly after any form of strenuous exercise.
A number of impressive performances this season have earned him an international recall, though, regardless of the ongoing issues surrounding his fitness.
He has joined up with Capello's squad ahead of a friendly date with Slovakia and a 2010 World Cup qualifier against Ukraine and will be hoping to build on his haul of 19 caps.
MonitoredThe Football Association has promised Tottenham that King will not be pushed too hard, meaning he is unlikely to feature in both of the upcoming games.
"The England management have spoken to Tottenham Hotspur FC and explained that they will take no risks at all with Ledley King," said an FA spokesman.
"They fully understand the player's injury situation but they wanted to have a close look at him in the team environment as Ledley has not previously been part of a Fabio Capello squad.
"He will be monitored during the week by the England and Tottenham Hotspur medical staff before any decision on training or playing is made."
King has not played for England since turning out in a Euro 2008 qualifier against Estonia almost two years ago.
He was included in Capello's first squad, for a friendly against Switzerland, but was forced to withdraw through injury.