A civilian contractor who died of 'cardiac episode' during rocket attack on Iraq base was a U.S. national, AFP reports citing Pentagon.

The contractor died after at least 10 rockets slammed into a military base in western Iraq hosting U.S.-led coalition troops on Wednesday.

The attack on the sprawling Ain al-Assad base in Iraq's western desert came after several weeks of escalating U.S.-Iran tensions on Iraqi soil.

It also comes just two days before the first-ever papal visit to the country by Pope Francis, who said he would still make the visit so as not to "disappoint" the Iraqi people.

Ain al-Assad hosts both Iraqi forces and U.S.-led coalition troops helping fight the Islamic State group, as well as the unmanned drones the coalition uses to surveil jihadist sleeper cells.

AFP cites security sources to have said the rockets were Iranian-made Arash models, which are 122mm artillery rockets and heavier than those seen in similar attacks.