The interview came as UK citizens prepare to decide whether or not their country should stay in the European Union on June 23. Bertelsmann Foundation is Germany's largest private fund dealing with pressing public problems.
"There is a risk that those who enthusiastically do not support the sanctions will become stronger without Britain," Weiss said.
According to diplomatic sources, the UK, the Baltic States and Sweden staunchly advocate maintaining the economic sanctions against Russia.
In contrast, Hungary, Cyprus, Greece, Italy, Slovakia and France have called for the partial or total abolition of the so-called 'restrictive measures' in addition to trade lobbies in Germany and elsewhere. Austria in turn stands for the normalization of relations with Russia.
Earlier, Russian Central Bank head Elvira Nabiullina told the CNBC that she does not "see any risks for the Russian economy resulting from a possible Brexit."
"There is no direct consequence for the Russian economy because we have a fairly low level of mutual trade with the UK and don't maintain a significantly high level of cooperation in the financial sphere," she said.
Relations between Russia and the West deteriorated over the situation in Ukraine in 2014. The EU imposed an increasingly severe series of anti-Russian sanctions that year. Russia responded by restricting imports of food products from those countries which had imposed the sanctions against Moscow.
In June 2015, Russia prolonged the food embargo until August 5, 2016, in a move that was preceded by the same step by the EU.
On June 23, UK nationals are set to vote in a referendum on the country's EU membership, after Prime Minister David Cameron and the leaders of the 27 EU member states agreed in February 2016 to grant the United Kingdom a special status within the bloc.