SOFIA, Bulgaria (Agencies) - NATOs Secretary General has ruled out any cross-border raids into Pakistan by the alliances troops in Afghanistan. Jaap de Hoop Scheffer said Thursday that the mandate of the 47,000-strong NATO force is strictly limited to Afghanistan. Taliban militants in Pakistans Swat Valley, near the Afghan border, have been tightening their grip on a neighbouring district closer to the Pakistani capital, Islamabad. Scheffer spoke to reporters in Sofia after talks with Bulgarian President Georgi Parvanov and PM Sergei Stanishev. In his remarks, Scheffer praised Bulgaria, which joined the alliance five years ago, as a staunch NATO ally. He stressed that NATO will continue its open-door policy to all countries that meet membership criteria.