ISTANBUL: Turkey and Armenia plan to sign an agreement Saturday establishing diplomatic ties in hopes of ending a century of acrimony over their bloody past and reopening their border, but nationalists on both sides are seeking to derail its implementation.

Better ties between Turkey, a regional heavyweight, and poor, landlocked Armenia are a key goal of President Barack Obama. They could help reduce tensions in the troubled Caucasus region and facilitate its growing role as a corridor for energy supplies bound for the West.

The contentious issue of whether the killing of up to 1.5 million Armenians during the final days of the Ottoman Empire amounted to genocide is only hinted at in the agreement, which calls for diplomatic ties for the first time and the opening of the sealed border within two months.

Some vague wording in the agreement merely sets the stage for further talks, and could be up to interpretation or dispute even if the two parliaments ratify the agreement as expected.

The foreign ministers of both countries are expected to sign the deal in Switzerland, which has hosted six weeks of talks between the foes.

U.S. Secretary of State Hillary Rodham Clinton is expected to attend. Russian Foreign Minister Sergei Lavrov will participate in the ceremony in Zurich on Saturday, the Interfax new agency said.

About 10,000 protesters rallied in Armenia's capital Friday to oppose the planned signing. The marching demonstrators carried placards with slogans such as "No concessions to Turks!" and "No bargaining on genocide!"

"Even if the documents are signed tomorrow, that will mark the beginning of our struggle against their ratification in parliament and their implementation," said protest organizer Kiro Manoian of the opposition Dashnak-Tsutyun party.

A tour of Armenian communities by Armenian President Serge Sarkisian sparked protests in Lebanon and France, with demonstrators in Paris shouting "Traitor!" and decrying plans to establish ties with Turkey. On Thursday, dozens of angry Armenians also staged protests in central Yerevan, the Armenian capital, burning papers meant to symbolize the agreement.

The agreement calls for a panel to discuss "the historical dimension" — a reference to the genocide issue — that will include "an impartial scientific examination of the historical records and archives to define existing problems and formulate recommendations."

That clause is viewed as a concession to Turkey because Armenia has said that genocide was confirmed by international historians, and further discussion could lead to deadlock. Turkey denies genocide, contending the toll is inflated and those killed were victims of civil war.

"Given Turkey's ongoing denial of the Armenian genocide, it makes affirmation that much more important," said Bryan Ardouny, executive director of the Armenian Assembly of America, part of the powerful Armenian diaspora.

Another source of dispute is Nagorno-Karabakh, an enclave in Azerbaijan that is occupied by Armenian troops. Turks have close cultural and linguistic ties with Azerbaijan, which is pressing Turkey for help in recovering its land. Turkey shut its border with Armenia to protest the Armenian invasion of Nagorno-Karabakh in 1993.

Turkey wants Armenia to withdraw some troops from the enclave area to show goodwill and speed the opening of their joint border, but Armenia has yet to agree, said Omer Taspinar, Turkey project director at the Brookings Institution in Washington.

"We may end up in a kind of awkward situation where there are diplomatic relations, but the border is still closed," Taspinar said.