MOSCOW (AP) — The presidents of Belarus and Russia met Friday to discuss deeper economic ties between the two close allies amid mounting concerns in the Belarusian capital of Minsk that Moscow ultimately wants to subdue its neighbor.

The meeting in the Russian city of St. Petersburg was the second encounter this month between Russian President Vladimir Putin and his longtime Belarusian counterpart, Alexander Lukashenka.

Greeting Lukashenka at the start of Friday’s talks, Putin said some progress on resolving outstanding issues has been made. But Russian Economics Minister Maxim Oreshkin said after the talks the two sides had failed to resolve key differences over oil and gas.

The negotiations have triggered opposition protests in Belarus, where many fear that closer ties with Russia could weaken Belarus’s independence. Such concerns were fueled by Moscow’s 2014 annexation of Ukraine’s Crimean Peninsula and its support for a separatist insurgency in eastern Ukraine.

Over 1,000 demonstrators rallied in the Belarusian capital Minsk on Friday, holding placards that read “First Crimea, then Belarus” and “Stop Annexation!”

Putin, who marks two decades in power later this month, has remained coy about his political future after his current presidential term ends in 2024. He dodged a question Thursday if he could potentially extend his rule by shifting into a new governing position to become the head of a union between Russia and Belarus.

The idea alarms some residents of Belarus.

“We will not allow Putin to become the president of a new Russia-Belarus state in 2024. We will never come back to the empire,” said Pavel Severinets, the organizer of Friday’s protest in Minsk.

Police allowed the unsanctioned protest to proceed unimpeded, even though Belarusian authorities routinely crack down on opposition rallies.

“Lukashenka doesn’t want to become a Russian provincial governor,” said 20-year-old student Pyotr Rudkevich, one of the protesters on Friday.

Russia and Belarus signed a union agreement in 1997 that envisaged close political, economic and military ties, but stopped short of forming a single nation.

Lukashenka, who has ruled Belarus for more than a quarter-century with little tolerance for dissent, relies on cheap Russian energy and loans to shore up his country’s Soviet-style economy.

The Kremlin has recently raised the pressure on Belarus, increasing energy prices and cutting subsidies. Russian officials say Minsk should accept closer economic integration if it wants to benefit from lower Russian energy prices.

See:Death toll rises to two in Moscow shooting targeting Russian security officers

In an apparent bid to win concessions, Lukashenka on Friday emphasized Belarus’s role as Russia’s military ally and security partner, an argument he has used repeatedly in the past to secure subsidies from Moscow.

“We have created a single defense space and our security agencies gave worked in close contact,” Lukashenka told Putin at the start of their talks.

But the Russian president has signaled that such tactics won’t work this time. He argues that Belarus can’t get Russia’s domestic prices for its oil and gas unless it agrees to closely coordinate its economic and financial policies and create interstate structures.

“It’s a huge work, and it can be done only if there is a political will shared by both sides,” Putin said at his annual news conference on Thursday.

Read on:Putin defends Molotov-Ribbentrop pact, says it was the West, not Russia, that appeased Hitler