SINGAPORE, Feb 3 (Reuters) - Asia's middle distillates markets started the week with upbeat trading activity, both onscreen and offscreen, with spot February sales also underway from a handful of refiners, although traders were still assessing the knock-on effect of U.S. tariffs.

There is a possibility of China jet fuel flows to the U.S. being affected given the blanket ban, but volumes have been sporadic in the past week and will probably not make a big impact on markets for now, one trade source said.

Meanwhile, February sales activity continued from some northeast Asia and India-based refiners, while Indonesia's Pertamina sought for spot gasoil and jet fuel. MDIS/TENDA

Refining margins GO10SGCKMc1 surged to two-week highs of around $16.5 a barrel, given the rollover in the active trading month to March and firmer paper market prices.

Cash differentials GO10-SIN-DIF fell by nearly 30 cents to 40 cents a barrel as a result of lower-priced offers, mainly from Middle East oil major Aramco, against a backdrop of a narrowing backwardation between February and March.

A sell-off in the paper markets was mostly seen for February-March spreads, per some trade sources.

Regrade's JETREG10SGMc1 discount widened to a more than one-week high as strength in gasoil marktes surpassed jet fuel.

SINGAPORE CASH DEALS O/AS

- No deals for both fuels

REFINERY NEWS REF/OUT

- PBF Energy PBF.N said on Sunday its 156,400 barrel-per-day (bpd) Martinez, California refinery was shut down after a fire on Saturday.

- Lyondell Basell Industries LYB.N has shut a crude distillation unit (CDU) and a coker at its 263,776 barrel-per-day (bpd) Houston refinery, said Executive Vice President Kim Foley during a Friday conference call.

NEWS

- U.S. President Donald Trump's trade tariffs on Canadian and Mexican oil imports will offer European and Asian refineries a competitive advantage against their U.S. rivals, analysts and market participants told Reuters.

- Oil prices jumped on Monday after U.S. President Donald Trump imposed tariffs on Canada, Mexico and China, raising fears of crude supply disruption from the two biggest suppliers to the U.S., but the prospect of lower fuel demand capped gains. O/R

- The new tariffs imposed by U.S. President Donald Trump on imports from Canada, Mexico, and China are likely to have a limited near-term impact on global oil and gas prices, Goldman Sachs said in a note on Sunday.

- Russian oil product exports from the Black Sea port of Tuapse are set to rise to 799,000 metric tons in February, up 10.9% on a daily basis from the 798,000 tons scheduled for January, two traders said on Monday.

PRICES

(Reporting by Trixie Yap; Editing by Sonia Cheema)

((trixie.yap@thomsonreuters.com;))