Stephen Watkins will be in a Warsaw court Wednesday, seeking the return to Canada of his two boys _ Alexander, 10, and Christopher, 8.
The 40-year-old Newmarket, Ont., man was granted custody of the children after he split up with his wife, Edyta Watkins. She and the boys vanished in March 2009.
A Canada-wide arrest warrant for abduction was issued for the boys' mother, and her name appeared on the RCMP's most wanted list. York Regional Police allege the mother and children drove into the U.S. and then flew to Germany.
In the summer of 2011, Edyta Watkins and the boys were tracked down in Poland, the woman's native country.
But last December, a Polish court ruled against sending the boys back to Canada. Watkins is appealing that decision.
The court's ruling was based on its conclusion that it would be detrimental for the children to return to Canada as they had integrated fully into Polish society.
But Watkins has maintained his sons still speak more English than Polish and that he has secured the support of Canadian agencies that would help his sons re-settle into their home in Newmarket.
He argues that Poland has recognized Canadian court orders that show he has sole custody of the children and has acknowledged that international law had been broken.
Poland doesn't have an extradition treaty with Canada, but it's party to the Hague Convention, which is meant to expedite the process of returning abducted children.
"I am working hard not only to get my own abducted sons home but also trying to set (a) precedence in the country of Poland to see many internationally abducted children returned to their home countries," Watkins wrote in an email to The Canadian Press on Sunday.
He has urged Prime Minister Stephen Harper to raise the issue with his Polish counterpart, Donald Tusk, when the two leaders meet in Ottawa this week.
"The fact remains, an international crime has been committed against my sons, other Canadian children and children from many countries worldwide."
A spokesman for junior Foreign Affairs Minister Diane Ablonczy said that since learning of the Watkins' situation consular officials both in Poland and in Canada have been providing assistance.
"Our government takes cases involving children extremely seriously," John Babcock said in an email Sunday.
"Consular officials are also actively engaging with local authorities, the province and the police on this case. We will continue to work with our partners towards a resolution in the best interest of the children involved."
To bolster his case this week, Watkins has asked the National Recognized Missing Children Organization of Poland to speak at the hearing.
He is also seeking the presence of Reunite International, the British charity specializing in the movement of children across international borders, at Wednesday's hearing.