ANKARA (AFP) - Turkey's Prime Minister offered his condolences on Wednesday, April 23, 2014, over the massacre of Armenians during World War I, calling it "our shared pain", the country's most significant overture yet over the deeply divisive episode.

Prime Minister Recep Tayyip Erdogan's statement, on the eve of the 99th anniversary of the start of mass deportations of Armenians in 1915, is the first such overt comment by a Turkish leader over the killings, considered by many as the first genocide of the 20th century.

He acknowledged that the events of 1915 had "inhumane consequences" but also said it was "inadmissable" for them to be used as an excuse today for hostility against Turkey.

"The incidents of the First World War are our shared pain," said Mr Erdogan in what Turkish media described as an unexpected statement that was issued in several languages, including Armenian.

Armenia has been trying to get Turkey to recognise the killings of up to 1.5 million people under the Ottoman Empire as genocide.

But Turkey puts the death toll at 500,000 and says they died of fighting and starvation during World War I, categorically rejecting the term "genocide".

"Millions of people of all religions and ethnicities lost their lives in the First World War," Mr Erdogan said.

"Having experienced events which had inhumane consequences - such as relocation - during the First World War, should not prevent Turks and Armenians from establishing compassion and mutually humane attitudes towards one another.

"It is our hope and belief that the peoples of an ancient and unique geography, who share similar customs and manners, will be able to talk to each other about the past with maturity and to remember together their losses in a decent manner.

"And it is with this hope and belief that we wish that the Armenians who lost their lives in the context of the early 20th century rest in peace, and we convey our condolences to their grandchildren," he said.

Mr Etyen Mahcupyan, a well-known Turkish columnist of Armenian descent, called the Prime Minister's statement "a first".

"It's very important. This reference to the suffering and offering of condolences, it's a first - symbolic even," he told CNN-Turk.

And Washington welcomed what it said was "Prime Minister Erdogan's public acknowledgement of the suffering that Armenians experienced in 1915".

"We believe this is a positive indication that there can be a full, frank and just acknowledgement of the facts, which we hope will advance the cause of reconciliation between Turks and Armenians," State Department spokesman Jen Psaki said.

The arrest and massacre of 2,000 Armenian leaders accused of collaborating with the Ottoman Empire's enemy Russia began in Istanbul on April 24, 1915, and in less than a year hundreds of thousands of people were forcibly displaced, their possessions seized and many killed.

A century on, the killings still fuel bitter controversy, often upsetting relations between Turkey and the West.

But there have been gradual signs of change in Turkey, with Foreign Minister Ahmet Davutoglu last year calling the events of 1915 to 1916 a "mistake" and an "inhuman act" during a trip to the Armenian capital Yerevan.

"It is indisputable that the last years of the Ottoman Empire were a difficult period, full of suffering for Turkish, Kurdish, Arab, Armenian and millions of other Ottoman citizens, regardless of their religion or ethnic origin," Mr Erdogan's statement said.

"Nevertheless, using the events of 1915 as an excuse for hostility against Turkey and turning this issue into a matter of political conflict is inadmissible," he added.

Erdogan's condolences came as he and his Islamic-rooted Justice and Development Party faced headaches on a number of other fronts, including a damaging corruption scandal and lingering anger from massive protests last year against what critics say is the government's creeping authoritarianism.

But Turkey has seen strong economic growth during Mr Erdogan's 11-year rule, and the Prime Minister's party scored a sweeping victory in local elections last month.

The nearly century-old Armenian massacre remains an extremely sensitive issue both in Turkey and abroad. Armenia and a vocal Armenian diaspora have lobbied for international recognition of the events as a genocide.

The issue has been a stumbling block for Turkey's long-held dream of joining the European Union.