A thirsty passenger on a cruise to Singapore has dispatched an SOS after being told beer and wine supplies are running out.

Five days out from the final destination, the situation aboard P&O's Pacific Jewel sounded dire.

A passenger claimed beer supplies had all-but run dry and wine stocks were almost depleted.

She said passengers were not allowed to bring alcohol onto the ship from the ports they visited and the cruise company was not going to restock the vessel.

"As well as low, mid and tap beer running out already, we have been advised by wait staff that all beer will be out of stock completely in 24 to 48 hours,” the passenger said.

"As wine is nearly finished as well, all wine packages can't be fulfilled.

"There are a huge amount of disgruntled passengers."

A P&O spokeswoman conceded the full selection of drinks were not available.

"Pacific Jewel is on her final voyage before leaving the fleet next week in Singapore but there’s no doubt we’ve got to do everything possible to make sure our guests can toast the ship’s final journey,” she said.

“We are disappointed that the usual drink selection is not available for our loyal guests, and our crew are working hard to fix this as soon as possible."

It is understood there is beer and wine on board but some of popular brands and mixers had run out.

It is expected the ship will be restocked during its next scheduled stop today.

The cruise left Fremantle on March 1 and is due to dock in Singapore on Tuesday after stopping at several Malaysian ports during the coming days.

It is the Pacific Jewel’s final voyage before the ship is replaced in the P&O fleet by the Star Princess.