International Development Secretary Justine Greening spoke Sunday as the U.K. faced mounting calls to do more to help migrants fleeing war and poverty in the Middle East and Africa. British charities and the leaders of opposition parties urged the government to let 3,000 more children start a new life in Britain. Human rights groups and local activists say the fence and police patrols along Greece's 200-kilometer border are forcing asylum-seekers from Syria and other conflict areas to pay hefty sums to smugglers and risk their lives to reach Europe by sea. Riot police set up the blockade in the border village of Kastanies, where several hundred activists burned a European Union flag and chanted "open the borders." Human rights groups and local activists say the fence and police patrols along Greece's 200-kilometer border are forcing asylum-seekers from Syria and other conflict areas, to pay hefty sums to smugglers and risk their lives to reach Europe by sea. Two migrant boats sunk in the eastern Aegean Sea earlier this week, killing at least 46 people, including more than a dozen children. Open the borders, are planning to travel in a bus convoy to the edge of a military area that includes the border fence, and onto a nearby border crossing point.