BAGHDAD (AFP) - Initial results from Iraq's provincial elections held on Saturday are to be released next week but the final outcome will take several weeks, the electoral commission chief said. "The preliminary results will be known next week but the final results will only be known in several weeks because it's a new and complex electoral system," Faraj al-Haydari told a press briefing after polls closed at 1500 GMT. The UN special envoy to Iraq, Staffan de Mistura, described the turnout as "heavy" but declined to provide exact figures until Sunday. "In the last election we gave percentages after the closure of the poll and they were not correct. We will not repeat the same mistake today," Haydari said, adding that the turnout would be announced on Sunday at 1000 GMT. Haydari stressed that only the Electoral Commission would tally he results. Iraqis voted in provincial elections in a crucial test for a nation struggling to emerge from years of sectarian strife and to strengthen its fledgling democracy. Security for the country's first ballot since 2005 was extremely tight with Iraqi police and military deployed in force as part of ramped-up measures aimed at preventing militant attacks and turnout was forecast to be high. But six policemen and a civilian were injured in a bombing in the mainly Shia Turkmen town of Tuz Khurmatu north of Baghdad. About 15 million people are eligible to vote to elect councils in 14 of Iraq's 18 provinces. Polling was to close at 1400 GMT but was extended by an hour. Results are expected to start rolling in on Tuesday. He said an expected high turnout would be an indicator of "the Iraqi people's trust in their government and in the elections" and "proof that the Iraqi people are now living in real security." Security has much improved in recent months, but insurgents still mount attacks on civilians and security forces, especially in the mainly Sunni Arab areas of Diyala province and the northern city of Mosul. More than 14,400 candidates are standing for 440 seats in councils, which appoint the provincial governor and oversee finance and reconstruction, with a combined budget of 2.5 billion dollars. Meanwhile, hundreds of Iraqi Kurds stormed an electoral commission office in northeast Iraq on Saturday claiming they were displaced residents of Khanaqin and demanding to vote, an official said. "The Kurds entered the election commission office and asked to vote because they said they were people displaced by Saddam Hussein," an official from the electoral commission told AFP. During Saddam's reign tens of thousands of Kurds were forced to relocate to the Kurd regions in northern Iraq, as part of the dictator's Arabisation plans. Meanwhile, the Iraqi journalist who hurled his shoes at former US president George W. Bush in Baghdad has voted in secret from his prison cell in the country's provincial election, a court official said. "Muntazer al-Zaidi voted on January 28," an official with the Central Criminal Court of Iraq told AFP. "Nobody was allowed to ask him whom he would vote for so it would not be considered as a way of trying to influence his choice." The journalist for the Al-Baghdadia television faces charges of "aggression against a foreign head of state during an official visit." If convicted he faces up to 15 years in jail.