ZURICH (Reuters/AFP) - Turkey and Armenia signed a landmark peace accord on Saturday to restore ties and open their joint border after a century of hostility stemming from the World War One mass killing of Armenians by Ottoman forces. But in an indication of the many pitfalls that lie ahead of its implementation, the ceremony was delayed for more than three hours after it hit a snag over last-minute disagreements with statements, forcing US Secretary of State Hillary Clinton to engage in intense discussions with the two sides. Turkeys Foreign Minister Ahmet Davutoglu and his Armenian counterpart Edward Nalbandian signed the Swiss-mediated deal in Zurich at a ceremony attended by Hillary, European Union foreign policy chief Javier Solana, Russias Foreign Minister Sergei Lavrov and Frances Foreign Minister Bernard Kouchner. The Armenian and Turkish Foreign Ministers shook hands after signing the two protocols in a ceremony at a university in the Swiss city of Zurich. But the two ministers and US, Russian, French and Swiss foreign ministers immediately left the room and failed to make their scheduled statements after the signature. No problems, they signed, said French Foreign Minister Bernard Kouchner afterwards. The Turkish and Armenian parliaments must now approve the deal in the face of opposition from nationalists on both sides and an Armenian diaspora which insists Turkey acknowledge the killings of up to 1.5 million Armenians as genocide. Before the agreement was signed at the University of Zurich, Hillary returned to her hotel to help smooth over disagreements with Nalbandian over statements to be read at the ceremony. She then held a long telephone call with Davutoglu before meeting Nalbandian. It was not immediately clear what was the cause of the disagreements, but ties between the two neighbours are traumatised by the mass killings of Armenians by Ottoman Turks. Earlier, a US official said a new version of the Turkish statement had been brought to the hotel, breaking the impasse. At the end, neither Davutolgu nor Nalbadian made public statements. The delay left Solana, Lavrov and Kouchner waiting for more than two hours while the Americans met the Armenians at a nearby hotel. Flanked by other dignitaries, Davutoglu and Nalbadian sat at a table to sign the deal. Once they had signed several pages, they stood up and shook hands to applause and exchanged hugs and handshakes with the other ministers. The deal to normalise ties and reopen the border has faced fierce opposition from nationalists on both sides and the Armenian diaspora which insists Turkey acknowledge the killings of Armenians by Ottoman forces in World War One as genocide. A decades-old dispute between Turkeys ally Azerbaijan and Armenia over the disputed enclave of Nagorno-Karabakh had hung over the deal after talks between Azeri and Armenian leaders over the region ended without result on Friday. An accord would boost US ally Turkeys diplomatic clout in the volatile South Caucasus, a transit corridor for oil and gas to the West. But disagreements over the Ottoman killings - which Yerevan calls genocide, a term Ankara rejects - and Nagorno-Karabakh hang over the settlement. The deal sets a timetable for restoring diplomatic ties and opening their border. It must then be approved by their parliaments in the face of nationalist opposition and the powerful Armenian diaspora.