* TOKI the main developer of Syria border wall
* Investments in 2017 to remain broadly flat
* TOKI invested 12-13 bln lira in 2016
By Nevzat Devranoglu and Orhan Coskun
ANKARA, Dec 9 (Reuters) - Turkey will finish building a wall along its 900 km (560-mile) border with Syria by next April, the head of one of its main developers said on Friday, in an attempt by Ankara to prevent Islamic State from entering the country.
State housing developer TOKI, better known for low-cost, high-rise apartment blocks in Turkey's major cities, is building two thirds of the wall along the border with northern Syria, where Turkish forces launched an operation in August to drive back Islamic State and Kurdish militia fighters.
"The wall will be completely finished by March or April. The costs are not high, and we are building extra border security roads behind it, as well as towers, which are crucial for our security," TOKI president Ergun Turan told Reuters.
Construction along sections of the wall started in 2014 in a bid to combat smuggling and illegal migration. Close to three million Syrians have sought refuge in Turkey since the start of the Syrian civil war almost six years ago.
Ergun meanwhile said he expected TOKI to build a total of 64,200 housing units in Turkey this year, above its initial 60,000 target. It aims to build another 65,000 in 2017, he said.
TOKI's investments in 2016 would come in at between 12-13 billion lira ($3.46-3.75 bln), just under half of it for housing and the rest on government projects including stadiums, hospitals and schools. Investment in 2017 would also be around 13 billion lira, Ergun said.
The agency is playing a leading role in government efforts to rebuild parts of southeastern Turkey, which have seen heavy fighting between the military and Kurdish militants.
Ergun said around 7-8,000 homes would be completed in the worst-hit areas in the new year, with a further 10,000 in the east and southeast later in 2017.
Government redevelopment plans for the largely Kurdish region are controversial. Amnesty International said this week that thousands of people were still unable to return home in one district, a year after authorities imposed a round-the-clock curfew in the battle against the militants.
TOKI owns nearly half of Turkey's biggest developer, Emlak Konut, and together they led a campaign to boost home sales after a failed coup in July hurt the economy.
The government has reduced taxes on some home purchases and made regulatory changes in recent months to try to lower mortgage rates in a bid to boost the housing market.
$1 = 3.4710 liras Writing by Ece Toksabay; Editing by Nick Tattersall and Alexander Smith