BAGHDAD (Reuters) - Hundreds of additional troops were sent into al-‘Ayadiya on Wednesday, as Iraqi forces came under increasing pressure to clear Islamic State fighters from their final position in the group’s former stronghold of Tal Afar, military officials said.

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Iraqi forces have been facing an unexpectedly tough battle in the small town, 11 km (7 miles) northwest of Tal Afar.

“We have to finish the battle before Eid, whatever it takes,” said Army Lieutenant Colonel Adnan al-Saidi. “We are coming under tremendous pressure from top commanders.” The Muslim holiday of Eid al-Adha begins on Thursday evening.

“We will take back al-Ayadiya even if we have to level all houses and buildings used by Daesh,” Saidi said, using the Arabic acronym for IS.

The fighting in al-Ayadiya has been described by some Iraqi troops as “multiple times worse” than the battle for Mosul, the former de facto IS capital in northern Iraq. The city was flattened in nine months of grinding urban warfare before it was recaptured in July.

Colonel Kareem al-Lami said breaching the militants’ first line of defense in al-Ayadiya was like opening “the gates of hell”.

Iraqi army and Federal Police troops, backed by Shi’ite paramilitaries, began fighting house-by-house in the center of the town earlier on Wednesday.

“Our soldiers now are engaging in a street fight with the militant group in al-Ayadiya,” Lieutenant General Qasim Nazzal told state television, adding that fighters in groups of three were barricaded inside “every single house and building”.

The terrain does not allow tanks to enter, so infantry soldiers have been using light weapons and grenades, Colonel Salah Kareem told Reuters.

Tal Afar had a pre-war population of more than 200,000. Several thousand are believed to have fled in the weeks before the battle started. According to the United Nations, more than 30,000 had fled since April.

Tal Afar became the next target of the U.S.-backed war on Islamic State following the recapture of Mosul the city where the group had declared its “caliphate”” over parts of Iraq and Syria in 2014.