Police and protesters clashed at Barton Moss minutes after judges in the Court of Appeal agreed to review a decision to evict an anti-fracking camp.
Campaigners attempted to slow-march in front of lorries destined for a drilling site, which is being tested for shale gas.
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Greater Manchester Police said "inquiries are ongoing to fully understand the circumstances of the incident."
Business Secretary Greg Clark said talks with Peugeot's boss over a potential Vauxhall takeover were both "constructive and reassuring".
He served in Margaret Thatcher's Cabinet as Home Secretary in 1989 and was also a former Governor of Bermuda.