Army heads are calling for recruits from the armed forces to man an anti-terror squad responsible for domestic security.

A defence source last night said the recruitment drive was prompted by "a surge in the global war on terrorism".

The unit would also be responsible for dealing with any security threats at the 2011 Rugby World Cup.

More than 60,000 overseas visitors are expected for the six-week tournament in September and October 2011.

Twenty countries will participate in the 48-game event, the third largest international sports event in the world.

An advertisement in this month's Army News said "international developments" had heightened the need for "an effective on call counter-terrorist capability" in New Zealand.

Army, Navy and Air Force personnel are encouraged to join the group, which is known as the Counter Terrorist Tactical Assault Group.

Another army source said recruits had been called for on previous occasions.

In 2006, it was reported the CTTAG was formed after the SAS struggled to recruit enough personnel to cover an increasing international workload and fulfil its counter-terrorist role at home.

CTTAG training was tough but, unlike the SAS, did not have an emphasis on "breaking in" an individual.

Instead, the unit focuses on building teamwork, improving shooting skills and helping squad members overcoming phobias such as fear of heights.

Terrorist attacks such as that on the Sri Lanken cricket team in Pakistan this month were evidence of the need for security at large-scale sports events, the source said.

The security bill for the Winter Olympics in Vancouver, Canada, next year is expected to be hundreds of millions of dollars.

The Army News advertisement said it was intended the New Zealand SAS group "will continue to deliver the current range of Special Forces capabilities, [and] an enhanced Counter Terrorist Tactical Assault Group will provide the critical domestic counter terrorist role for the New Zealand Defence Force".

The Officials Committee for Domestic and External Security Co-ordination currently deals with terrorism threats in New Zealand and the Police Commissioner is accountable for the operational response to threats to national security.

The CTTAG will work with existing anti-terrorist organisations including police groups such as the special tactics groups, armed offender squads, diplomatic protection squad and specialist search group.