As insurgents of United Naga Council threatened to block the key Manipur-Nagaland road link, Centre today informed Rajya Sabha that national highway between the two states is open with trucks plying on it. Mr. P Chidamabaram informed the House that enough security forces have been positioned and strict instructions given that the trucks of the Food Corporation of India carrying foodgrains and of the oil companies carrying fuel would be plied on the highway.He said the government is also prepared to provide security for convoys of private truckers who have complained about extortions. The Home Minister said Manipur Chief Minister had called a meeting with all groups representing the hill districts but the UNC did not attend it.The United Naga Council UNC, an appex body of the various Naga tribes in Manipur, has imposed a 20-day economic blockade on the two National Highways of Manipur from Wednesday morning. The UNC is demanding among other things, dissolution of the newly elected Autonomous Hill District Councils, lifting of all prohibitory orders from the Naga inhabited areas and a judicial enquiry into the May 6 incident at Mao Gate in Senapati district. No commercial vehicles are plying on the Imphal Dimapur National Highway since Wednesday morning.