"Terrorists and agitators are pursuing the agenda to hinder progress and prosperity of Pakistan. There is no difference between them," Sharif said while inaugurating a 393-kilometre-long Sukkur-Multan motorway in Sukkur.
"People should think twice about which side they want to be on...What do terrorists do? They wish to halt progress in Pakistan," he said in harshly-worded remarks.
Referring to the sit-ins staged by the opposition, he asked: "What is the agenda of those who agitate?"
The premier said that the country would not have lagged behind in progress if there was no sit-in politics.
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The motorway is a part of the Peshawar-Karachi motorway and falls under the China-Pakistan Economic Corridor. It will be built with financial assistance from China.
Sharif said the assistance from China would have come earlier if the Pakistan Tehreek-e-Insaaf party led by Imran Khan had not staged a "sit-in" in Islamabad.
A war of words between opposition leaders and the government has escalated over the past few weeks, with opposition parties holding anti-corruption rallies and building pressure on the premier to step down.
Major opposition parties this week asked the prime minister to present himself and his family for accountability after the Panama leaks claimed his sons and daughter held stakes in off-shore companies worth millions of dollars.