sentences:  However, as of November 2006, Miyeegombyn Enkhbold, Mongolia's prime minister, officially denied the existence of such camps.One scholar estimated that 500 North Korean refugees enter Mongolia each month, along with some legal migrant labourers who come under an inter-governmental agreement to work in light industry and infrastructure projects.In 2013, the Mongolian President Tsakhiagiin Elbegdorj visited North Korea, and the two countries expanded economic ties, particularly with regard to oil refining.