Armenian protesters say the killings must be fully acknowledged
Turkey and Armenia are preparing to sign a historic agreement normalising relations between them after a century of hostility.
But the deal has been met by protests in Armenia, where many people say it does not fully address the 1915 killing of hundreds of thousands of Armenians.
The two countries remain deeply divided over the killings under Ottoman rule during World War I.
The accords are due to be signed after months of Swiss-mediated talks.
US Secretary of State Hillary Clinton is among the dignitaries expected to attend the signing in Zurich, Switzerland.
Russian Foreign Minister Sergei Lavrov, French Foreign Minister Bernard Kouchner and the EU's High Representative for the Common Foreign and Security Policy, Javier Solana, are also expected to be at the ceremony.
Several thousand people protested on Friday in the Armenian capital, Yerevan, saying that Turkey should recognise the 1915 killings as genocide before ties are restored.
"The international recognition of the Armenian genocide will be hindered by this signature, or ratification," said Vahan Hovanissyan, a member of parliament for the nationalist Dashnak Tsutyun party.
One protester told the BBC he was not opposed to the opening of the border, but was "against the setting up of a commission that will allow Turkey to further postpone declaring the killings as genocide".
Hundreds of thousands of Armenians died in 1915, when they were deported en masse from eastern Anatolia to the Syrian desert and elsewhere. They were killed by Ottoman troops or died from starvation or disease.
Hillary Clinton is expected to attend the signing ceremony in Zurich
Armenians have campaigned for the killings to be recognised internationally as genocide - and more than 20 countries have done so.
Turkey admits that many Armenians were killed but it denies any genocide, saying the deaths were part of the widespread fighting that took place in World War I.
A roadmap for normalising relations between Turkey and Armenia was agreed in April.
Under the accords expected to be signed on Saturday, the two countries will resume diplomatic ties and open their shared border.
The agreement also calls for a joint commission of independent historians to study the genocide issue.
Turkish Prime Minister Recep Tayyip Erdogan has said the deal will still need parliamentary approval in Turkey and Armenia after being signed by their foreign ministers.
HAVE YOUR SAY
It is in the best interest of both countries that they forget about the past and start a new era in their relationship
Abdul Malik Niazi, Kabul, Afghanistan
Turkey closed its border with Armenia in 1993 because of its war with Azerbaijan over the disputed region of Nagorno Karabakh.
The BBC's Tom Esslemont in Yerevan says that despite their protests, the anti-protocol activists are struggling to make their voices heard.
Most Armenians seem to feel their country has been too isolated since the Turkish border closed in 1993 and are ready for it to reopen, says our correspondent.
But even those in favour of the border reopening feel that they have not been properly consulted by the government, he says.