UPDATE 1-Turkey and Iraq to sign gas deal, discuss security

* Neighbours expect to deepen energy, security ties

* Not clear if gas intended for Nabucco pipeline

* Talks on PKK rebel group expected

(Adds details, background)

BAGHDAD, Oct 15 (Reuters) - Turkey and Iraq will sign an agreement on Thursday to transport Iraqi natural gas to Europe via Turkey, as the two neighbours look to expand energy and security ties, Turkish officials said.

Turkey's Prime Minister Tayyip Erdogan and a large government delegation was in Baghdad on Thursday where they planned to meet Iraq's Prime Minister Nuri al-Maliki and other government officials.

Turkish officials said the two countries also planned to sign deals extending an agreement over an Iraq-Turkey oil pipeline as well as an accord to complete new power lines and boost the capacity of existing cross-border lines.

Erdogan, whose country has improved ties with Iraq in recent years, said before his departure to Baghdad that he also expected to hold talks on boosting cooperation in the fight against the Kurdistan Workers' Party (PKK) guerrilla group, which uses bases in northern Iraq to launch attacks on southeast Turkey.

Some 40,000 people have been killed in Turkey since the PKK took up arms to carve out an ethnic homeland in southeastern Turkey. Turkey and Iraq have increased cooperation in the fight against the PKK.

It was not immediately clear whether the gas intended for export to Europe would pass through the planned 7.9 billion euro Nabucco pipeline project, which has been conceived to cut Europe's dependence on Russian gas.

Iraqi's al-Maliki has said that Iraq could supply some 15 billion cubic metres of gas through the Nabucco.

(Reporting by Pinar Aydinli in Baghdad; Writing by Thomas Grove and Ibon Villelabeitia; Editing by William Hardy)