SHANGHAI - China's coal exports in May tumbled 39 percent from a month earlier to 1.19 million tonnes, their lowest in more than 11 years, according to official data released by the General Administration of Customs on Thursday.

Total exports in the first 5 months of the year fell 43.1 percent from a year earlier to 10.53 million tonnes, the official data showed.

The monthly exports in the past two months were barely half the monthly average for the last 20 years.

Annual term price negotiations between Chinese exporters and Japanese utilities have dragged on for months, affecting shipments to one of the top destinations for Chinese coal.

"Chinese coal is not competitive in terms of prices, which has caused the export volume to drop. But coal imports were likely still at a high level in May," said Judy Zhu, an analyst at Standard Chartered.

The customs is expected to release May coal imports data later this month.

Imports hit an all-time high of 9.16 million tonnes in April, but rising freight fees and international coal prices are squeezing margins.

"Freight fees have risen too much, nearly 40 percent higher than April. We have stopped importing thermal coal from Australia, as its price has risen," said a trader based in Guangdong.