Pistorius claims he mistook her for an intruder at his home.
Van Zyl, who is due to meet Pistorius on Tuesday, has also not ruled out the prospect of the athlete competing at August's
The International Association of Athletics Federations (IAAF), which is the body responsible for the World Championships, told BBC Sport last week that Pistorius, who has competed at both Olympics and Paralympics, would be "free to run" in the event on the "basis of the 'innocent until proven guilty' principle".
Pistorius - the athlete
• Pistorius had his lower legs amputated at the age of 11 months, having been born without a fibula in either leg
• His parents, Henke and Sheila, were advised that having the amputation done before he had learnt to walk would be less traumatic
• By the age of two, Pistorius had his first pair of prosthetic legs
• He played water polo and rugby in secondary school. He also played cricket, tennis, took part in triathlons and Olympic club wrestling and was an enthusiastic boxer
• In June 2003, he shattered his knee playing rugby and on the advice of doctors took up track running to aid his rehabilitation
• Pistorius has won six Paralympic gold medals
"First and foremost, he has to be ready to train and compete," said van Zyl. "Once he is ready and feels he is up for training again, we will have him back on the track.
"He is a world-class athlete and if he does compete again this season - and if he achieves the qualifying times - it is something you would have to consider, but it is early days.
"He hasn't trained for eight weeks, so to get back into competition form he would have to train first and it will take him time to get back to that level."
Nova, the company which organises the Manchester City Games, said there were "no plans to invite him over" after the change in his bail conditions. Pistorius withdrew from the event, to be held on 25 May, after being charged.
It is also believed he is unlikely to be invited to compete at the London Anniversary Games in July at the Olympic Stadium.
At London 2012, Pistorius became the first double amputee to run at an Olympics. as he took part in both the 400m and 4x400m.
He then won gold medals in the T44 400m and T42-46 4x100m at the Paralympics, as well as silver in the T44 200m.
The International Paralympic Committee told BBC Sport it would wait until after Easter to discuss the matter of Pistorius competing at the
IPC Athletics Championships,
which take place in Lyon in July.
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