* NDRC repeats emphasis on longer term coal contracts
* Comes at start of peak winter-heating season (Adds detail)
BEIJING, Nov 29 (Reuters) - China has again urged coal suppliers and buyers to sign more medium- and long-term contracts, amid robust demand for the fuel during the peak winter-heating season.
The National Development and Reform Commission (NDRC) said in a document published on Wednesday that medium- to long-term contracts should make up 75 percent of supply deals signed by government and municipal authorities as well as power firms.
It added that railways, ports and shipping firms should make handling such contract business a priority. Contracts should run for at least a year.
The NDRC had already ordered coal companies and utilities in April to fix 75 percent of their total coal purchases through long-term contracts.
But Chinese thermal coal futures have still surged this year, recently rallying about 7 percent since early November to 655.6 yuan ($99.29)per tonne.
The NDRC also warned that contracts must be strictly fulfilled, and that it would strengthen supervision of contracts of more than 200,000 tonnes. ($1 = 6.6030 Chinese yuan renminbi) (Reporting by Beijing Monitoring Desk and Dominique Patton; Editing by Shri Navaratnam and Joseph Radford)