Flags and posters are seen in Amsterdam for Wednesday’s nonbinding referendum on the E.U.-Ukraine trade deal. (Peter Dejong/AP)

Dutch voters on Wednesday rejected a trade deal between the European Union and Ukraine in a referendum that served as a rallying point for anger over the increasing powers of the bloc’s leadership in Brussels.

About 61 percent of voters said “no” to the E.U.-Ukraine pact, the Associated Press reported. Voter turnout was 32.2 percent, just above the threshold of 30 percent required for the referendum to be valid, broadcasters in the country reported after all the votes were counted.

The trade deal — already approved by parliaments across the 28-nation European Union — essentially creates a free-trade zone with Ukraine and marks another significant step in that country’s integration with the rest of the continent.

The Dutch referendum’s effect on the trade pact is unclear. Portions of the accord are already in place, and overturning it would require all E.U. members to agree — a highly unlikely scenario.

In his televised early reaction to the vote, Prime Minister Mark Rutte said: “If the turnout is above 30 percent, with such a big victory for the ‘no’ camp, you can’t just go ahead and ratify the treaty.” He said he would discuss the result in his cabinet, at the European Union and in the Dutch parliament, a process that could take “days if not weeks,” the AP reported.

The vote was closely watched as a bellwether of growing mistrust and criticism within the E.U., which has struggled to deal with a huge migrant influx and debt crises in member states, notably Greece.

Opponents of the deal played on fears of growing Russian pressure on Europe and NATO. Critics argued that Russia could indirectly benefit from greater E.U. commercial openings to Ukraine, where pro-Russian separatists hold territory in the east. In 2014, Russia also annexed the Crimean Peninsula amid the tensions.

Supporters of the trade deal claimed just the opposite — that it deals a blow to Moscow by strengthening E.U. bonds in a former Soviet republic.

“To vote ‘no’ is to endorse the Russian effort to destabilize the European Union from within, and to encourage the continuation of Russia’s wars in the E.U.’s neighborhood,” wrote the ­historian Timothy Snyder, an advocate for a Europeanized Ukraine.

In 2014, the pact helped set off uprisings that eventually led to Ukraine’s civil war. The deal was initially signed but then opposed by the pro-Russian government of President Viktor Yanukovych, who was driven from office by the unrest.

According to Peter van Ham, a senior fellow at the Clingendael Institute, a think tank based in The Hague, voters in the “no” camp in the Netherlands come from a variety of perspectives.

“It’s a mixed bunch,” he said. “Some vote with their guts, and some vote with their brains.”

There are those, van Ham said, who oppose specific components in the deal, such as hydraulic fracturing, also known as fracking, or the potential to open doors for displaced Ukrainians on a continent already beleaguered by the largest migrant crisis since World War II.

But there are others who are dissatisfied with what they ­perceive to be faulty E.U. promises and bureaucratic incompetence.

“The point is more of a political nature,” van Ham said. “It’s an opportunity to signal a lack of trust, a signal that the electorate has had enough.”

The referendum was largely engineered by the Dutch GeenPeil, a Euroskeptic social-media group whose name means “not a clue,” a jab at the European Union.

The Netherlands will hold elections next year, in March, and the “no” vote in the referendum was expected to bolster
the rising popularity of Geert Wilders, a leading anti-immigrant firebrand who bears similarities to France’s conservative National Front party leader Marine Le Pen.

Wilders is perhaps most famous for his criticism of Islam, including calls to ban the Koran in the Netherlands.

The “yes” campaign was not helped by revelations this week in the Panama Papers — leaked documents from a Panamanian law firm and follow-up reporting from a worldwide consortium of journalists into tax havens and shell companies. The report detailed the extent of offshore accounts held by Ukrainian President Petro ­Poroshenko.

For many critics of the deal, the papers have justified the findings of Transparency International, which has repeatedly assigned Ukraine a high corruption rating.