SINGAPORE (Reuters) - Top oil exporter Saudi Arabia may cut prices for crude grades it sells to Asia for a second month in August, tracking weakness in Middle East benchmark Dubai, trade sources said on Friday.

The potential price reduction for Asia, which accounts for about 80% of Saudi's oil exports, underscores the pressure faced by OPEC producers as non-OPEC supply continues to grow while the global economy faces headwinds.

The official selling price (OSP) for flagship Arab Light crude sold to Asia in August may fall by 60 cents to 80 cents a barrel from July, possibly to the lowest since April, four sources at Asian refineries said in a Reuters survey.

The respondents expect slightly deeper price cuts for heavier grades - Arab Medium and Arab Heavy - than Arab Light on improving supply from Mexico and Canada.

Comparatively higher prices for Saudi oil prompted refiners in China to reduce imports from Saudi Arabia for a third straight month in July.

The potential price cuts for August are expected to track a narrowing in backwardation for Dubai's monthly price spreads by 85 cents this month from May, a sign of tight supply easing. Backwardation refers to higher prompt prices than those in future months.

Global crude futures have been supported by OPEC+ cuts and peak summer demand in the northern hemisphere, which is expected to lead to a supply deficit this quarter although analysts expect more supply to come from non-OPEC producers in the Americas. [O/R]

The average margin at a complex refinery in Singapore, the bellwether for Asian refiners, stabilised at $3.62 a barrel in the past 15 days after falling for two straight months, LSEG data showed.Saudi crude OSPs are usually released around the fifth of each month, and set the trend for Iranian, Kuwaiti and Iraqi prices, affecting about 9 million barrels per day (bpd) of crude bound for Asia.

State oil giant Saudi Aramco sets its crude prices based on recommendations from customers and after calculating the change in the value of its oil over the past month, based on yields and product prices.

Saudi Aramco officials as a matter of policy do not comment on the kingdom's monthly OSPs.

Below are expected Saudi prices for August (in $/bbl against the Oman/Dubai average):

JULY Change est.AUG OSP

Arab Extra Light +2.20 -0.65 +1.55

Arab Light +2.40 -0.80/-0.60 +1.60/+1.80

Arab Medium +1.95 -0.80/-0.70 +1.15/+1.25

Arab Heavy +1.20 -0.80/-0.65 +0.40/+0.55

Source: Reuters, trade