Union officials have dismissed the Government-ordered independent inquiry into industrial disputes as politically motivated and a distraction to the "cost of living crisis".
A Unite spokesman said: "Vince Cable may not have noticed but the Grangemouth dispute has been settled. This review is nothing more than a Tory election stunt which no trade unionist will collaborate with."
GMB general secretary Paul Kenny agreed, saying the announcement "seems like another sop to the Tory backbenches".
He said the "real scandal at Grangemouth" concerned the chairman of the refinery's owners Ineos, Jim Ratcliffe, and how he was "able with impunity to hold the country to ransom".
More top news
Kelly Osbourne has quit Fashion Police after the E! show came under fire over a comment Giuliana Rancic made about Zendaya's dreadlocks.
The death of Boris Nemtsov hits particularly hard because he represented what post-Communist Russia might have become.
Dad Kyle Johnson claims a bus driver threatened to kick him and his two-year-old son Ethan off unless the deaf toddler quietened down.