German Chancellor Angela Merkel had an "in-depth" conversation with Russian President Vladimir Putin over the worsening tensions between Moscow and Kyiv, her spokesman Steffen Seibert said on Saturday.

Merkel joined French President Emmanuel Macron, who also met Putin separately on the sidelines of the G20 summit of the world's biggest economies in Argentina, in demanding the release of the Ukrainian sailors captured by Russia's navy last weekend. Putin insisted their cases would be dealt with by the courts.

Russia captured several Ukrainian navy vessels on Sunday in the Kerch Strait, which links the Sea of Azov and the Black Sea. The area is located off the Crimean Peninsula, a territory Moscow annexed from Ukraine in 2014.

At a press conference later on Saturday, Putin said Ukraine was not interested in a peaceful resolution to the conflict and called the governing party in Kyiv a "party of war."

"As long as it's in power, tragedies of this type and the war will continue," Putin added.

Read more: Russia-Ukraine skirmishes: Storm warning on the Black Sea

Moscow insisted the boats had illegally crossed into Russian waters, while Kyiv filed a complaint in the European Court of Human Rights over what it said was Russian aggression.

During her talks with Putin, Merkel pushed for "freedom of shipping into the Sea of Azov." The two leaders agreed to initiate talks between Germany, France, Russia, and Ukraine to reduce tensions in the region.

Kyiv, which also accuses Russia of supporting separatist rebels in eastern Ukraine, declared martial law following the incident and banned Russian men between 16 and 60 from entering the country.

Ukrainian President Petro Poroshenko said Saturday that the "Kremlin is further testing the strength of the global order" to see if the international community will allow Russia to assert that the Sea of Azov and the Black Sea are Russian territorial waters.

Read more: Ukraine denies entry to 100 Russians as tension with Moscow escalates

Hopeful that trade tensions will subside

Merkel also said she hoped talks between the United States and China would help resolve trade tensions between the two countries. Merkel met with Chinese President Xi Jinping and they discussed both trade and partnership.

US President Donald Trump and Chinese President Xi Jinping are due to meet later Saturday on the sidelines of the summit.

The chancellor said all countries are "affected indirectly when Chinese-American economic relations are not as frictionless as a world order requires."

Trump, meanwhile, has canceled a planned meeting with Putin because of the latest standoff with Ukraine.

Read more: No winners in US-China trade spat — says who?

Merkel also spoke of the need to reform the world body that regulates international trade disputes, which was raised during the G20 talks.

"Everyone is in agreement that the WTO (World Trade Organization) should be reformed. That is an important agreement," she told reporters.

Merkel also held talks with Indian Prime Minister Narendra Modi.

Concerns are rising that the two-day G20 summit — which represents more than 80 percent of the world's economy and global trade — would end on Sunday without a final communique, due to a number of US objections, including statements over trade, migration and climate change.

mm/jm (AFP, AP, dpa, Reuters)

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