"One thing is absolutely clear, if the Minsk ceasefire accord does not work then (EU) member states and the European Commission are quite prepared to move to new sanctions," Merkel said.
Speaking in Brussels after talks with European Commission head Jean-Claude Juncker, Merkel said they had discussed the need to restore Ukraine's territorial integrity, a key part of the Minsk agreements agreed by Kiev, Moscow and the pro-Russian rebels in the east.
Merkel and French President Francois Hollande flew to the Belarussian capital last month to broker the ceasefire.
"There is a link between current sanctions and complete implementation of Minsk so that Ukraine officials will have access to their own frontier," Merkel said in Brussels.
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"Territorial integrity can only be restored if you have Ukraine officials on the Russian border; that is what we are working on."
The United States and European Union say Russia has backed the rebels with troops, arms and technical assistance to win control of the border and large areas of eastern Ukraine.
The US and EU have imposed steadily tougher sanctions against Russia over the Ukraine crisis, including costly restrictions on key sectors of the struggling Russian economy such as the banks and defence industries.
Merkel was initially very reluctant to go too far for fear of damaging Germany's hugely important political and economic ties with Moscow.
The shooting down in July of a Malaysia Airlines plane over eastern Ukraine with the loss of nearly 300 lives, blamed on the rebels, changed Berlin's stance to support sectoral sanctions but Merkel has been guarded in going further.