ANKARA, March 20 (Reuters) - Turkey's state broadcaster plans to launch an Armenian-language radio station, Anatolian state news agency said on Friday, amid tentative moves by Turkey and its neighbour Armenia towards restoring diplomatic ties.

Relations between the two countries are haunted by the killing of Armenians by Ottoman Turks during World War One, which Armenia says amounted to genocide. Ankara accepts many Armenians were killed, but denies genocide was committed.

Since then large numbers of Armenian speakers have left Turkey but some 40-50,000 remain, mostly in Istanbul.

"At this stage, we will refrain from any comments," an Armenian Foreign Ministry spokesman said when asked about the report of the planned radio station on Friday.

The announcement comes as some U.S. lawmakers, ahead of a visit by President Barack Obama to Turkey on April 6-7, are renewing a push to brand the 1915 massacre genocide.

Ankara has warned that a new resolution by the U.S. Congress could seriously hurt Washington's ties with NATO ally Turkey.

It also argues such a resolution would derail the drive to mend relations with Armenia, including moves to open the border.

Anatolian said the Armenian-language channel should go on air in "two to three months." The official day of remembrance in Armenia is April 24.

The genocide issue, which caused U.S.-Turkish relations to plummet in 2007, threatens to complicate Obama's trip as Washington hopes to work closely with Turkey on Afghanistan, Iraq, the Middle East and the Caucasus.

During his 2008 campaign for the White House, Obama referred to the killings of Armenians in World War One as genocide. Obama is now confronted with a choice between breaking a campaign pledge or risking defence ties with Turkey.

Turkey and Armenia have no formal diplomatic relations but officials have held recent tentative discussions.

Anatolian said state-run Turkish Radio and Television Corp (TRT), which launched a television channel in the once-banned Kurdish language in January, also planned to launch a Kurdish radio channel.

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