BEIJING (Reuters) - China will further open up sectors such as telecommunications, airports and oil and gas exploration to private firms, China's cabinet said on Wednesday, in an effort to halt a record slide in private investment growth.

Chinese policies to encourage private investment had been beset by problems, the cabinet said in a statement following a meeting led by Premier Li Keqiang, following a nationwide investigation of challenges faced by private firms.

China would introduce measures to improve private investment, including dealing with issues such as unfair competition, a lack of market access and difficulty getting financing, the cabinet said.

Investment by private firms slowed to a record low for the January-May period, with growth cooling to 3.9 percent from 5.2 percent in Jan-April and double digits last year. Private investment accounts for about 60 percent of overall investment in China.

(Reporting by Beijing monitoring desk; Writing by Elias Glenn; Editing by Nick Macfie)