LONDON, May 12 (Reuters) - Northwest European gasoline refinery margins gained 19 cents to $29.43 a barrel on Tuesday as supply tightened.

• About 10,000 metric tons of E5 gasoline barges traded in the Argus window as BP sold to TotalEnergies.

• An additional 4,000 tons of E10 gasoline barges changed hands, with Sahara Energy and Shell selling to Exxon.

• Brazil's state-run oil firm Petrobras PETR3.SA is studying projects for its next business plan aimed at making the country self-sufficient in gasoline and diesel, CEO Magda Chambriard said.

• Some independent refiners in China's eastern province of Shandong are cutting fuel output on crumbling margins after the Iran war drove up crude costs as they battle weak domestic demand and excess products, trade and refining sources said.

• In the U.S., President Donald Trump said on Monday he backs reducing the 18.4-cent federal gasoline tax.

• Meanwhile, EU-27 and UK exports of gasoline and blending components stood at 341,000 bpd in May, compared to 939,000 in April, data from Kpler showed.