Punjab's opposition Aam Aadmi Party (AAP) on Monday demanded a high-level impartial inquiry by either the CBI or a High Court Judge into the extortion racket going on at the Bathinda oil refinery.The government led by Chief Minister Amarinder Singh remains unmoved despite reports about the levy of 'goonda tax' by certain leaders of the ruling Congress and the Shiromani Akali Dal, Leader of Opposition and senior AAP leader Sukhpal Singh Khaira told the media here.He said Sam (India) Built Well Pvt Ltd and Ashok Bansal, owner of a ready-mix concrete plant, sent written complaints to the district authorities, Amarinder Singh and the Punjab and Haryana High Court Chief Justice to seek action against those openly demanding 'goonda tax'."As per their complaints, there is a nexus between mafia collecting 'goonda tax' or protection money and politicians of both the Congress and the Akali Dal. It is unfortunate that the extortion has been going on ever since the oil refinery had been set up. It snowballed into a major controversy when politicians from the Congress began armtwisting companies and contractors," Khaira said.Khaira said Aman Sidhu of Bangi Kalan village in Talwandi Sabo is the main conduit for collecting 'goonda tax' at the behest of his political masters -- earlier Akali leaders and now Congress leaders considered "close" to the Chief Minister's son Raninder Singh.He said the name of a brother-in-law of Finance Minister Manpreet Badal had also cropped up in the racket.The Chief Minister had on February 15 directed the Director General of Police to crackdown against the culprits but the extortion continued thereafter also.The issue was raised during a Cabinet meeting by some Ministers, who urged Amarinder Singh to take cognisance of the matter, following which the Finance minister rued he was being vilified in the whole affair.