New Zealand's withdrawal from Iraq looks "inevitable" following Iranian missiles strikes against bases hosting United States troops, former Minister of Defence Wayne Mapp says.

The NZDF is, meanwhile, investigating claims New Zealand's base in Iraq has also been hit.

Deputy Prime Minister Winston Peters is now expected to issue a statement on the issue this afternoon.

United States officials have confirmed more than a dozen surface-to-surface missiles had been fired at two Iraqi military bases, with Iranian state television describing it as a revenge attack over the killing of top military commander Qassem Soleimani in an air strike by the United States.

Details of damage or injuries were not immediately available.

New Zealand currently has 45 Defence Force personnel stationed at Camp Taji, near the city, where they have trained Iraqi soldiers since 2015. Five more personnel are based in Baghdad.

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The NZDF was on Wednesday afternoon investigating reports Taji had also been hit, an NZDF spokesman said.

The Government last year announced the mission would be withdrawing by June, 2020.

But concerns have been raised about the safety of New Zealand troops and that they could get caught up in Iranian strikes amid rising tension and rhetoric following Soleimani's killing.

New Zealand Defence Minister Ron Mark learned of the attack from media on Wednesday, with the news breaking as he spoke to reporters.