FOLLOWING a government circular co-signed by the Ministry of Economy and Finance last week warning mobile-phone firms they would have to pay tax even if profits fall on the back of low tariffs, Minister Keat Chhon has backed up the call, saying there will be a clampdown on the sector. “We will not allow any company to be free from paying tax,” he said Tuesday after a conference on the 2010 budget in Phnom Penh. The matter had been discussed with Minister of Telecoms So Khun, he added, who also signed the letter, dated September 29. It was sent to all mobile firms, the Council of Ministers and Prime Minister Hun Sen.