DHAKA, May 13: Visiting US Assistant Secretary of State for South Asia Christina Rocca on Thursday criticized extra-judicial killings in Bangladesh, and said that such incidents were not acceptable to the United States and international community. During her talks with Prime Minister Khaleda Zia and opposition leader Sheikh Hasina, she also expressed concern over incidents of violence and reported killings and attempts on political leaders. Ms Rocca hoped that all cases of political violence would be thoroughly investigated. She said it was necessary for the authorities to improve performance and curb corruption to be able to compete for the millennium challenge account.