The Pakistan team has been questioned, finger printed and had to undergo DNA tests in connection with investigations being carried out by authorities in Jamaica into the murder of coach Bob Woolmer, who was strangled to death on Sunday.
The former England player, 58, had been found unconscious in his Kingston hotel room and died later in hospital.
The Pakistan squad, who were knocked out of the World Cup after a shock loss to Ireland last Saturday, have had their departure delayed since Thursday.
PCB director of cricket operations Saleem Altaf told Reuters their delay was due to a non-availability of seats.
"The basic problem they are facing is finding seats from London to Pakistan on the World Cup's official carriers. They have not been held up because of the investigations," he said.
"We are now trying to arrange a chartered flight for them from London onwards."
He denied that the investigating authorities had refused permission for any player(s) to fly out of Jamaica because of ongoing investigations.
"Obviously it has been very stressful for the players. The last week has been a very painful experience for all of us," he said.
Altaf said the PCB had yet to receive anything in writing regarding the investigations but would continue to cooperate.
"Once the team is back we will get a report from the manager and also talk to the players. We need to start putting our cricket back on track as soon as possible," he said.