Zain Iraq, the country's biggest mobile phone company, has invested about $20 million in its efforts to list on the local stock exchange, its chief executive said on Thursday.

The Iraqi unit of Kuwait mobile phone operator Zain is required to list on the Iraq Stock Exchange (ISX) as part of its $1.25 billion operating licence, obtained in 2007.

Rivals Asiacell, owned by Qatar Telecom, and Korek, in which France Telecom and Kuwait's Agility have stakes, are also required to list and have said they are working towards flotation.

All three companies missed an initial deadline of August 2011.

"We have invested a lot of money. We have invested over $20 million in this. We have hired lawyers, we have brought (in) bankers," Emad Makiya, chief executive of Zain Iraq, told Reuters. "There are so many processes involved, so many things. It is not as easy as you think."

The first step for the three operators is to convert to shareholder-owned companies and then obtain approval from the ISX board and Iraq's securities commission.

So far, only Asiacell has transferred into a shareholders' company, the ISX chief executive said in April.

Zain has appointed BNP Paribas, Citigroup and National Bank of Kuwait to run its offering.

Iraq did not have a mobile phone market under Saddam Hussein and the sector has boomed since his fall from power in 2003, offering double-digit subscriber growth. It is the fastest growing industry in the war-battered country after oil.

Successful stock market listings for the three mobile operators would be seen as a triumph in efforts to create a diversified economy in a country still dominated by state-run companies.

Zain, which has about 12.5 million subscribers, announced on Thursday that it had dropped prices for all its tariffs in Iraq, lowering the price for all calls made between 8am and midnight by 30 percent.

Makiya said he was hopeful the mobile phone company would be granted a 3G operating licence this year and said that it planned to market more aggressively in the autonomous northern Kurdish region, where it lags behind its competitors.

"Our entry into Kurdistan was a bit late, but that doesn't mean we are going to stop investing," he said.

Zain started operating in Iraqi Kurdistan in early 2011. - Reuters