ATHENS, Nov. 4 (Xinhua) -- U.N. Secretary General Ban Ki-moon on Wednesday called on governments and international organizations to enhance their cooperation in dealing with challenges concerning global migration.

    In an address before the Third Global Forum on Migration and Development, the U.N. leader said migration was a modern challenge that can't be addressed unilaterally.

    The ongoing financial crisis, climate change and human trafficking are the three main challenges that "add to the urgency for action" in the issue of migration, Ban said.

    Ban said that in times of financial crisis, migrants usually face a higher possibility of unemployment. The number of migrants may also increase in the future because of climate change, he said.

    Meanwhile, Ban also stressed the protection of women and children who are always the most vulnerable victims of smugglers and sex exploitation.

    "One of the most beautiful words in the Greek lexicon is Philoxenia - friendship towards strangers," Ban said, "Let us take inspiration and work together to make it a global reality."

    Greek President Karolos Papoulias, Prime Minister George Papandreou and other high-level Greek officials also attended the meeting.

    The forum opened on Wednesday with the intention of advancing policies to help migrants settle in their new home countries.

    More than 250 representatives from governments and international organizations were expected to exchange views on issues related to migration and development.