The two leaders were scheduled to make statements before the talks, but there were no plans for a news conference afterwards.
Russian President Vladimir Putin and German Chancellor Angela Merkel discussed the conflicts in Ukraine and Syria, as well as Iran and a gas pipeline project that has drawn us ire during tough talks outside Berlin that ended with no clearcut progress.
"I am of the opinion that controversial issues can only be addressed in dialogue and through dialogue", she said before leaving for talks with the Russian leader.
Speaking on Saturday, Merkel said "Ukraine must continue to play a role in the transit of gas to Europe once Nord Stream 2 is in place".
The invitation surprised many in Vienna and Moscow, particularly at a time when the European Union is at odds with Russian Federation over its annexation of the Crimea region from Ukraine, and other issues.
"I would like to stress that the main thing is that the Ukrainian transit - which is traditional for us - meets economic demands", he said.More news: Ex-Spurs boss Sherwood: Zola ideal for Chelsea striker Morata
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The goal of the $11 billion Nord Stream 2 pipeline project is to double the existing pipeline's annual capacity of 55 billion cubic meters.
The United States, which opposes the pipeline project over concerns about increasing Europe's dependence on Russian natural gas, was not present, but could have a big say in the outcome, the Wall Street Journal reported.
Putin is facing the possibility of more US sanctions on Russian Federation imposed by Trump, and has an interest in softening or heading off any European support for them.
In July, Putin assured that Russia was willing to keep Russian flowing through Ukraine after the pipeline was commissioned, but without going into details on volumes or tariffs.
With protesters audible Saturday outside the guesthouse in Meseberg, Putin also raised the issue of humanitarian aid and funding for worldwide reconstruction in Syria.
Chancellor Merkel said it was important to avert a humanitarian crisis in Idlib, Syria and the surrounding region. Trump has pulled the USA out of the program and imposed new sanctions, saying that they will also hit foreign countries that keep doing business with Iran.
Putin was one of around 100 guests at Kneissl's wedding to businessman Wolfgang Meilinger in the picturesque village of Gamlitz in southeastern Austria.
Opposition politicians have accused Kneissl of undermining European Union foreign policy by inviting Putin.