Iraq's prime minister says his country needs greater support from the international coalition so it can "finish" the Islamic State group.

Haider al-Abadi says the "marked increase" in airstrikes, weapons deliveries and training has helped roll back the extremist group, but that more is required to rid Iraq of it once and for all.

His comments to journalists on Monday came as he boarded a flight to Washington where he and will meet with President Barack Obama.

Al-Abadi says Iraq's relationship with neighboring Iran is "very balanced" and that those at odds with Iran should not "throw their problems on us."

Both the United States and Iran are helping Iraq battle the Islamic State group, but insist they are not coordinating their actions on the battlefield.