By Andrea Thomas 

BERLIN--Germany's Chancellor Angela Merkel Monday stressed the need to prepare more sanctions against Russia because the risk stemming from the country's "unacceptable" behavior in Ukraine outweighs economic risks for German companies.

Her comments come after European Union leaders agreed late Saturday to draw up options within a week for possible new sanctions against Russia, with action to follow quickly unless Moscow takes clear steps to scale back its intervention in Ukraine.

"I have pointed to what these [sanctions] could mean for German companies. But I also have to say what it could mean if you are allowed to shift borders in Europe and attack other countries with your troops without facing any consequences. In my opinion, this is a much bigger risk than accepting certain disadvantages for businesses during a limited period," Ms. Merkel told reporters, after a meeting with officials from her conservative party.

"I believe it is necessary to prepare such sanctions and that possible disadvantages in no way outweigh those resulting from doing nothing."

Overall trade between Russia and Germany reached $100 billion last year and represented 3.3% of German exports.

Given Germany's other big trading partners, such as the euro zone and the U.S., economists and government officials have said the impact of sanctions against Russia would be limited as long as Moscow didn't cut off gas supplies to Germany, which imports more than a third of its gas from Russia.

Considerations to step up economic sanctions against Russia come amid European and U.S. leaders' growing frustration with Russia's moves in Ukraine over the recent months. They have said Moscow has aided pro-Russian rebels in eastern Ukraine and sent more than 1,000 troops into Ukraine territory, a claim that Russia has rejected.

Ukraine last week accused Russia of invading the country.

President Vladimir Putin, in an interview on state television Sunday, said Kiev should begin "substantive, meaningful negotiations, and not on technical issues, but on the political organization of society and statehood in the southeast of Ukraine."

Laurence Norman

in Brussels and Gregory L. White in Moscow contributed to this article.

Write to Andrea Thomas at andrea.thomas@wsj.com