ANKARA, Oct 9 (Reuters) - European Union candidate Turkey is due to sign on Saturday historic accords to normalise ties with Armenia, a step towards ending a century of hostility that will eventually include the reopening of their joint border.

Following is a summary of what the opening of the border would mean for predominantly Muslim Turkey.

DIPLOMATIC COUP

* Ankara can claim a diplomatic triumph if the neighbours see through a promise to restore ties after 100 years of hostility. Turkey and Armenia have no diplomatic ties because of hostility stemming from the mass killings of Armenians by Ottoman Turks during World War One. Turkey closed its border with Armenia in 1993 in solidarity with fellow Muslim Azerbaijan, then at war with Armenian-backed ethnic Armenians.

The EU and the U.S. President Barack Obama have stepped up pressure on Turkey and Armenia in recent months to normalise ties soon. While the EU has no specific policy regarding Turkey opening its border with Armenia, the bloc has said it would be beneficial for relations between the EU and Turkey as it would add to the overall stability of the South Caucasus, a transit corridor for oil and gas to the West. It would also offset Ankara's lack of progress toward EU membership in a number of key areas, including freedom of the press, freedom of religion and civilian oversight of the military.

The agreement calls for a joint commission of independent historians to study the genocide issue. Turkey is keen to rid itself of the stigma of genocide allegations, and the commission could produce a narrative acceptable to Turkey.

But even if Ankara and Yerevan ink the protocols, it is far from certain the accords will be implemented and their joint border opened soon.

REGIONAL CLOUT

The accords could see a re-alignment of interests in the South Caucasus, for centuries the backdrop for big-power rivalry over the strategic crossroads between East and West and its energy deposits in the Caspian Sea. If Ankara and Yerevan can move beyond the symbolism to re-establish normal relations and open the border it could have huge significance for Turkey's role as a regional power. It would bolster Turkey's credentials as a moderniser in the West and increase Ankara's sway and stabilising influence in the South Caucasus region, where Russia flexed its muscles last year by sending troops into Georgia. It would also extend NATO member Turkey's influence into Central Asia and win plaudits from the EU, which it wants to join, and the United States. Under a policy to expand its soft power towards the east, Ankara has also stepped up in recent years trade and political ties with Middle East countries, including Iraq, Syria and Iran, which could turn Turkey into a trade super corridor. Trade and investment in the region could rise living standards in Turkey's poverty-stricken southeast and help end a 25-year conflict with separatist Kurdish rebels.

The U.S., a close Turkey ally, gains in further stabilising a region vital for energy export to the West.

ENERGY

Western-backed pipelines shipping oil and gas from the Caspian Sea to Turkey's Mediterranean coast bypass Armenia and bend north instead to go through Georgia. With that route looking vulnerable after the Russian intervention, Armenia could be an attractive alternative route, benefitting Turkey. Turkey is positioning itself as an energy corridor for the West. It is part of the planned EU-backed multi-billion dollar Nabucco pipeline that would run through Turkey and cut Europe's reliance on Russian gas.

INVESTOR CONFIDENCE

The agreement itself is not market moving, but could have positive implications for investors for Turkey as it will bolster its role in the region. It will also help convince EU states opposed to Turkey's membership that Ankara is on the side of stability. Turkey is an attractive investment destination because of its geopolitical situation and its unique trade and economic links to the West, the Middle East, the Caucasus and Central Asia. An open border would also mean greater trade between Turkey, Europe and land-locked Armenia. (Compiled by Ibon Villelabeitia; Editing by Ralph Boulton)

AlertNet news is provided by