"At any major event from an Olympics to a World Cup of any sporting code there's always a perception that there's a greater risk."
To deal with this potential threat, Mr Key wanted to pass anti-terror laws before the Cup, which begins in New Zealand and Australia in February.
The main concern was that foreign fighters returning from conflict zones in the Middle East or individuals influenced by the militant group Islamic State (Isis) could carry out a terror attack here.
Officials are reviewing current laws which affect foreign fighters and the Government is seeking cross-party support for any changes.
Mr Key said New Zealand had a duty to protect its own citizens and visitors at the Cup.
The national terror threat level was raised last month from very low to low. The last time this occurred was immediately before the Rugby World Cup in 2011.
This week, Australia issued new travel advice to people making the pilgrimage to Gallipoli for next year's WWI centenary commemorations.
Australians were told to show a "high degree of caution" when travelling to Turkey, particularly near the borders with Syria and Iraq but also in the Gallipoli peninsula.
New Zealand's Ministry of Foreign Affairs did not follow suit but said it would be reviewing its advice for the Turkish region leading up to the centenary events. About 2000 Kiwis will travel to Anzac Cove for events in April.
Defence Minister Gerry Brownlee said the Turkish Government was "well aware" of the need for tight security at the historic event.
Returned Services Association national president B.J. Clark said he hoped the warnings about terror attacks would not cast a shadow on the events at Gallipoli.
Major events
• G20 summit - Brisbane, November 15-16
• Cricket World Cup - New Zealand/Australia, February 13-March 14
• WWI centenary commemorations - Gallipoli, Turkey, April 25.
