PARIS - Ties between France and Turkey, strategic allies and trading partners, abruptly unraveled Thursday after French legislators passed a bill making it a crime to deny that the mass killings of Armenians by Ottoman Turks nearly a century ago constitute genocide.

The bill strikes at the heart of national honor in Turkey, which denies the genocide label and insists that the 1915 massacres occurred during civil unrest as the Ottoman Empire collapsed, with losses on both sides. But it's seen as a matter of principle for some French politicians, and a matter of long-overdue justice for the 500,000 people in France of Armenian descent; many of them had relatives among the 1.5 million Armenians killed.

The French bill still needs Senate approval, but after it passed the lower house, Turkish Prime Minister Recep Tayyip Erdogan halted bilateral political and economic contacts, suspended military cooperation, and ordered his ambassador home for consultations.

Turkey argues that France is trampling freedom of expression and that French President Nicolas Sarkozy is on a vote-getting mission before April presidential elections.

France formally recognized the 1915 killings as genocide in 2001 but provided no penalty for anyone refuting that. The bill passed Thursday sets a punishment of up to a year in prison and a fine of 45,000 euros (about $59,000) for people who deny or "outrageously minimize" the killings, putting such action on par with denial of the Holocaust.

The diplomatic riposte by Turkey over the vote by lawmakers in France's National Assembly may get even tougher. It hurts ties as both NATO members are involved in international efforts for peace from Syria to Afghanistan.

France expressed regret over Turkey's response. "It is important, in the current context, that we keep the paths of dialogue and cooperation open," Foreign Minister Alain Juppe said in a statement.

Strains have plagued the two nations' relationship in recent years, in large part because Sarkozy opposes Turkey's bid to join the European Union. The bill reached the French parliament after Sarkozy visited Armenia in October.

The issue is dicey for any government that wants a strong alliance with Turkey, a rising power. President Obama has stopped short of calling the killings genocide.