A senior EU official said Reuters on Wednesday, Censor.NET reports.
Tusk is working with German Chancellor Angela Merkel and French President Francois Hollande on a compromise proposal on the future of EU sanctions that he believes all 28 EU leaders would support at a summit on Thursday.
"The direction of that proposal will go into building very strong links between full implementation of Minsk and sanctions that are already in place being in place until full implementation of Minsk," the official told reporters on condition of anonymity.
An uneasy ceasefire is in place in eastern Ukraine after a new truce agreement was agreed in Minsk last month.
Agreement of all EU governments is needed to renew economic sanctions on Russia expiring in July, but governments are sharply divided.
More hawkish member states wanted an agreement to extend those sanctions now, while other governments wanted to wait until a June summit to give the Minsk accord a chance to work.
Linking sanctions to full implementation of Minsk would effectively mean extending them at least until the end of the year, because the Minsk accord contains a year-end deadline for Ukraine to recover full control over its border.
The EU official said all governments were ready to agree that Merkel and Hollande, having helped negotiate the Minsk agreement, "should have a specific role in the process of defining further steps which should support implementation of Minsk".
"That is why right now Tusk is working together with Merkel and Hollande on that proposal," the official said.
One EU diplomat said leaders would likely agree at the summit to signal now that they would keep sanctions on Russia until the Minsk terms were fully met, while leaving a formal decision on renewing sanctions until June.
"It makes no sense to reduce the pressure on Russia ... if their commitment to the full implementation of Minsk hasn't been tested," he said. "We think there are clear advantages to sending a signal on rollover (of sanctions) early on."
A German government official said that implementation of the Minsk agreement was the benchmark for Berlin.
Merkel made clear when she met Ukrainian President Petro Poroshenko in Berlin on Monday "that the implementation of the Minsk agreement and sanctions are closely bound politically," the official said, speaking on condition of anonymity.