Human rights activists have criticized US pop singer Jennifer Lopez for singing Happy Birthday to the leader of Turkmenistan, who is accused of human rights violations.According to a BBC report, Lopez serenaded Gurbanguly Berdimuhamedov in the former Soviet Union country on Saturday night. She was performing at an event hosted by the China National Petroleum Corporation.Lopez's publicist said she would not have performed had she known there were human rights issues in the country.Turkmenistan's human rights record has been heavily criticized by various countries. Human Rights Watch describes the country as "among the most repressive in the world."After a United Nations visit last month, Assistant Secretary-General for Human Rights, Ivan Simonovic, said the country had made progress, but "a lot more work is needed to complete this process and to ensure practice is in line with international standards."Lopez, also known as J-Lo, performed a selection of her hits during the show on Saturday.A statement released by Lopez's publicist to The Associated Press said the event was not political, adding: "Had there been knowledge of human rights issues any kind, Jennifer would not have attended."The birthday serenade was a last-minute request made by the corporation to Lopez before she took the stage, and she "graciously obliged", the statement said.Lopez's performance fee was not disclosed and her publicist said she was not scheduled to perform at any other events in Turkmenistan.In 2007, Lopez was honoured by the human rights group Amnesty International for the film, Bordertown, set in Ciudad Juarez, the Mexican town at the centre of a decade of unsolved rapes and murders of young women. Lopez produced and starred in the film.