Health authorities in Iraq's Kirkuk region have screened a total of 800 people since a chemical attack carried out by the Islamic State group last week, officials said on Monday.

"The number of people who have sought treatment and been checked by the hospitals in Daquq and Kirkuk has topped 800," said Hussein Adil Abbas, the mayor of Taza.

IS last week fired a salvo of rockets armed with suspected chemical agents on the town of Taza, around 220 kilometres (135 miles) north of Baghdad.

The attack originated from the nearby village of Bashir, which is still controlled by the jihadists.

"Among the people who have been checked, 61 are receiving treatment and undergoing further testing. Seven of them have been transferred to Baghdad," Abbas told AFP.

Kirkuk health officials speaking on condition of anonymity have confirmed the figures.

A three-year-old girl has died as a result of injuries caused by the attack. Her funeral was attended by hundreds, some of them carrying placards to demand more protection from the government.

Local officials have said that IS used mustard agent in the attack but the samples are still being analysed and definitive results from the Organisation for the Prohibition of Chemical Weapons based in The Hague sometimes take months.

Civil defence teams have since Sunday been spraying and cleaning areas that might have been contaminated in last week's attack, the mayor said.

Several Taza families have left their town, fearing a fresh attack.

While the chemical agents used by IS so far have been among their least effective weapons, the psychological impact on civilians is considerable.

Prime Minister Haider al-Abadi has vowed the attack would not go unpunished and several air raids have already been carried out on Bashir over the past three days.

Tension between the Kurdish peshmerga who control Kirkuk and the Shiite militia groups also present in the area has delayed a coordinated military operation to oust IS from Bashir.