Kirk Bradley and Tony Downes, both 25, were travelling from HMP Manchester to Liverpool Crown Court when the van was attacked by armed men on 18 July.
They were on their way to a trial where they were facing firearms charges.
The Serious Organised Crime Agency (SOCA) believes the Liverpool men may be attempting to travel to Spain.
Mr Downes, known as Fat Tony, from Dovecot, and Mr Bradley, of no fixed address but formerly of Huyton, are accused of conspiracy to possess firearms with intent to endanger life and conspiracy to commit criminal damage with intent to endanger life.
They were standing trial alongside four other men but the hearing has since collapsed.
Mr Downes is known to be an associate of Kevin Parle, another fugitive on the Crimestoppers most wanted list, who is thought to be in Spain and is wanted in connection with two murders in Liverpool.
A spokesman for SOCA said: "These are dangerous men and it is very important that nobody approaches them.
"We are asking people who think they may have seen them to call Crimestoppers, either in Spain or in the UK.
"You can do this free, and completely anonymously. Our priority is getting these two back into custody as soon as possible."
The van the men were travelling in was attacked in Trinity Way, Manchester, last Monday.
The gang fled with the prisoners in a Saab, which was found abandoned about a mile away in Barrow Street, Salford.