Indonesia is now overwhelmingly China’s biggest overseas supplier of coal, with shipments hitting a record last month after Beijing loosened curbs on imports to tackle its power crisis. 

Cargoes of coking, thermal and brown coal from the Southeast Asian nation surpassed 21 million tons in September, from just over 17 million tons in August, and now account for about two-thirds of China’s total imports, according to customs data. Chinese buyers have been forced to tap other suppliers of the fuel to replace Australian exports banned almost a year ago after political relations with Canberra soured. 

But hopes that Mongolia could supply more coal—particularly the higher quality produced by Australia and used by steel mills—were dashed as pandemic restrictions in China’s neighbor saw cargoes sink below 1 million tons, according to the data.   

Indonesia’s benchmark coal price has hit record levels, bolstered by a surge in demand since June, when Beijing pledged to raise imports in an ultimately unsuccessful attempt to head off the power crisis that’s now gripping the country.

Late last year, China struck a three-year deal with Indonesian miners for $1.5 billion of the fuel as Beijing sought long-term options to displace Australian supplies. Indonesia provides a lot of low-grade brown coal, which has a price advantage but is both less efficient and worse for the climate.

Indonesia should continue to ship more to China as demand weakens from another key market, India, according to Bloomberg Intelligence analyst Michelle Leung. However, supply could still be prone to hitches. In recent months, Indonesia has told producers to prioritize domestic supplies, while mining activity has been constrained by flooding and the pandemic.

The price of one Indonesian variety of the lower-quality fuel hit $160 to $170 a ton this week, according to traders. That’s well up from $110 to $120 earlier this month. Supplies from the Southeast Asian nation remain tight due to weather-related disruptions, with sellers playing catch-up to meet prior commitments to buyers, the traders said.