Violence and intimidation are threatening efforts to draft a new Afghan constitution, Human Rights Watch says. In an open letter to President Hamid Karzai, the New York-based watchdog called on the Afghan Government to crack down on warlords. It said they were interfering with the selection of candidates to the loya jirga or grand council due to discuss the draft constitution in December. A spokesman for Mr Karzai said the government and the United Nations were happy with progress on the constitution. Human Rights Watch says a climate of fear exists in every region of Afghanistan. It says some candidates have received death threats and want to stay away from elections due to take place next year after the loya jirga has been held. It will debate the provisions of the new Afghan constitution, which is due to be made public imminently. The rights group collected its material during dozens of interviews conducted over the past three weeks. It says armed men and military commanders have threatened candidates in provinces in the north, forcing at least one of them to withdraw. In the western city of Herat political opponents of Governor Ismail Khan have been the target of assassination attempts, the letter to Mr Karzai says. Similar threats have been reported from Kandahar and Zabul provinces in the south. Human Rights Watch is calling upon the president to investigate those accused of making the threats and to speak out publicly against the violence. It is also urging him to bring in legislation disqualifying candidates if they are found guilty of intimidation. (BBC)