Growth in the country's eight core sectors surged to an over four-year high of 8.5 per cent in April this year. Output surged on the back of double-digit expansion in refinery products output and electricity generation. The eight core sectors had contracted 0.2 per cent in April last year, and grown 6.4 percent in March this year. According to Commerce Ministry data, output of refinery products spurted 17.9 percent in April, fertilizer production increased 7.8 %, steel output rose 6.1 %, cement production increased 4.4 %, and electricity generation surged 14.7 % during the month. But production of coal, crude oil and natural gas declined during the month.