LONDON, Dec 30 (Reuters) - Benchmark northwest European gasoline barge refining margins fell to about $9.9 per barrel on Thursday, pressured by a rise in regional stocks. Gasoline stocks held in independent storage in the Amsterdam-Rotterdam-Antwerp (ARA) refining and storage area rose by about 1.6% to 1 million tonnes in the week to Thursday, data from Dutch consultancy Insights Global showed. Naphtha stocks dropped sharply by over 20% to 163,000 tonnes amid strong demand from the petrochemical sector, according to Insights Global"s Lars van Wageningen. U.S. gasoline stocks (USOILG=ECI) fell by 1.5 million barrels last week to 222.66 million barrels, compared with analysts" expectations in a Reuters poll for a 0.5 million-barrel rise, Energy Information Administration data showed on Wednesday. U.S. oil refiners are expected to have 302,000 barrels per day (bpd) of capacity offline for the week ending Dec. 31, increasing available refining capacity by 6,000 bpd, research company IIR Energy said on Wednesday. ​ Gasoline (in tonnes) Trades (vol.) Bids Offers Prev. Trades Sellers Buyers Ebob Barges MOC Platts E5 $750 (2 barges) $759 Gunvor Varo Ebob Barges E10 Platts(fob ARA) Ebob Barges Argus E5(fob AR) $740 (10 KT) $737.25 (7KT) Litasco BP, Exxon Ebob Barges E10 Argus (fob AR) $755.75 (1KT) $749.25 (9KT) Glencore BP Jan swap fob ARA $741.50 $731.25 Premium Unleaded (fob ARA) $764 $752-$753 Shell, Varo BP Cargoes Cargoes (cif NWE) Naphtha Ebob crack (per barrel) $ prev. $ Brent futures Rbob Rbob crack