LONDON, July 20 (Reuters) - Northwest European gasoline refining margins eased by about $1 to $44.43 a barrel on Monday, remaining near a four-year high, as Yemen's Houthis announced a blockade on Saudi Arabia, threatening supplies through the Red Sea.

• A total of 6,000 tons of Eurobob E5 barges traded on Argus, with BP, ExxonMobil and TotalEnergies selling to Gunvor.

• A further 2,000 tons of Eurobob E10 barges traded, sold by Shell to BP, with Argus assessing an additional 1,000 tons.

• Exxon also sold an E5 barge to Trafigura in the Platts window.

• Yemen's Iran-aligned Houthis said on Monday they were imposing a naval blockade on Saudi Arabia, a move that opens a new front against the United States in its war on Iran and widens the threat to global energy supplies and trade beyond the Gulf.

• U.S. gasoline pump prices crossed the $4 a gallon mark on Monday as renewed hostilities with Iran further disrupt energy flows through the Strait of Hormuz, a critical route for global oil supplies.

• India has no plans to raise the ethanol content in gasoline beyond the current 20%, junior oil minister Suresh Gopi said on Monday, amid fears of further increases and criticism that the blend reduces efficiency and vehicle performance.

• China's June refined oil product exports improved from May, but still tumbled from the same period last year amid export restrictions that started mid-March to safeguard domestic supply in the wake of the Iran war.