Zaheer Khan, whose name did not figure in the list announced by Board of Control for Cricket in India (BCCI) earlier, joined the camp being held on the premises of National Cricket Academy (NCA).
The injury-hit Baroda left-arm seamer had returned home after a short stint with Surrey in England and the troubled bowler would now be looking to return to top fitness.
Others attending the camp include Ashish Nehra, Ajit Agarkar, Irfan Pathan, L Balaji, Avishkar Salvi and Amit Bhandari.
Emphasising that the focus would be on fitness-training, King said the bowlers would undergo normal training like core stability, flexibility, cardio-vascular and endurance. "The guys will do a bit of bowling and throwing," he added.
King said he would take stock of the fitness levels of the bowlers, and the progress they made during the off-season.
He said since the bowlers had taken a break, their fitness levels had gone down a bit which is inevitable and expected.
Meanwhile, four trainees of NCA -- V R V Singh, R P Singh, D K Mungraj and Saurav Sarkar -- have also joined the camp.
Others attending the camp are: Siddarth Trivedi, D T Kumaran, Munaf Patel, Sreesanth, S S Paul, S Mathur, N C Aiyappa, Gagandeep Singh, Joginder Sharma and Fazil Mohammed.
Earlier on Tuesday, the bowlers started the day with an hour-long Yoga session.