Prime Minister Stephen Harper met with his Polish counterpart Monday to discuss a new tax agreement intended to stimulate trade -- but the two leaders also delved into Europe's economic woes.

Harper and Prime Minister Donald Tusk first witnessed the signing of a new tax convention that will lower the rate of withholding tax between companies doing business in the other country.

"Canada is committed to strengthening its relationship with Poland by fostering an environment that will encourage growth and long-term prosperity for both countries," Harper said in a release.

But Harper stayed reserved over the eurozone's troubles.

"It's not my place to tell Europeans how to resolve problems within the European Union," he said at a press conference, standing next to Tusk.

"Obviously these problems remain serious. They've been with us since the financial crisis. And it is essential that they be addressed."

A stalemate in Greece has rattled financial markets around the world, as political parties appear unable to reach a power-sharing agreement after two weeks of talks.

But Harper said Poland has been doing well, despite economic difficulties in other countries.

"Largely due to Prime Minister Tusk's leadership, Poland is also the only EU country to have completely avoided a recession following the 2008-2009 global economic and financial crisis," Harper said.

Harper and Tusk also spoke about a Canadian man whose children have been living with their mother in Poland since 2009, when they vanished from Canada.

Stephen Watkins is currently in Poland fighting to convince local courts to send his sons home and uphold an Ontario court ruling which ordered the boys returned to their father.

Harper addressed the issue briefly in a news conference Monday.

"The Canadian government has been giving consular assistance and giving assistance to ultimately enforce a Canadian court order in this case, beyond that, as you know, the matter is before the courts, so I'm not sure I want to get too much into the details of an individual case," Harper said.

Watkins told Â鶹´«Ã½ Channel via Skype that he is fighting a battle that may only be won if Harper gets behind the effort and lobbies on his behalf.