SINGAPORE (Reuters) - Pakistan State Oil (PSO) bought 25,000 tonnes of 180-centistoke (cst) high sulphur fuel oil (HSFO), 30,000 tonnes of 380-cst HSFO and 10,000 tonnes of low viscosity fuel oil via tender, with the 180-cst portion concluded at a higher premium, traders said on Tuesday. All three cargoes were bought from Middle East trader Bakri International Energy for July delivery to Karachis FOTCO terminal. The 180-cst parcel was sold at a premium of $17.40 a tonne to Middle East spot quotes, while the 380-cst went for a premium of around $23.00 a tonne to Middle East spot quotes, both on a cost-and-freight (C&F) basis. The low-viscosity fuel oil was concluded at around $70.00 a tonne above Middle East spot quotes, (C&F), traders said. Pakistan State Oil last bought 780,000 tonnes of 180-cst HSFO from Bakri, Middle East trader Fal Oil and European trader Trafigura for July-September delivery at $15.00-16.00 at tonne above Middle East spot quotes, while another 120,000 tonnes of low sulphur fuel oil were transacted at a premium of $53.00-$55.00 to Middle East spot quotes, all on a C&F basis.