PHUKET: Authorities conducted a raid at dawn today on Phuket Prison in a hunt for illegal weapons, drugs and telephones. The swoop was part of a national campaign.

Phuket Prison came up clean, but for the media who were allowed to watch the process, it was an insight into the overcrowded jail's cramped quarters.

One prison officer told us that the place was so sardine-tight that if a prisoner got up in the middle of the night to go to the toilet, they were likely to find their bed space taken when they returned.

A random drugs test of 104 prisoners produced five positive samples, but all were attributed to new prisoners who had just arrived and hadn't had the drugs pass through their systems yet.

Cigarettes were the prime contraband. Smoking is banned. We watched as officers went through the empty dormitories, giving bedding a thorough inspection.

There were plenty of spoons and a copy of 'Sexy Nuts' magazine, but the only worrying item we saw was a penknife with a blade about four centimetres long.

The central quadrangle at the prison was jam-packed with men when we entered, so much so that other groups squatted on the ground both to the left and to the right.

The 35 foreigners among the male prisoners hung out in a group that sat along one side, although some also mingled in the main group.

The only faces we recognised were the two young Swedes charged with last year's murder of a countryman.

But there is, so we were told, at least one Australian on the inside. Perhaps for him especially there was a sense of his country's convict history when eight prisoners, shackled because of their tendency to violence, shuffled down the stairs to join the throng.

The noise is what will stay in our minds, a clinking, clanking sound unlike any other.

Phuket prison, 111 years old, now holds 1615 inmates, said Phuket Prison Commander Rapin Nichanon, a reformer who would like to see the national government either spend 900 million baht on a new jail at Bang Jo or 100 million baht on expanding the existing facility.

To walk in at daybreak to see the prisoners all assembled in a tight space was to understand the problem.

This is the reason why Britain colonised Australia. The British prisons were full to the point where unseaworthy ships at anchor in the Thames River were used to hold the overflow.

Even petty crimes brought hefty seven-year sentences in the 1700s, just as any drugs crime brings jail time in Thailand today.

The pressure to enforce the no-tolerance policy on drugs comes at a cost - crowded jails where reform and rehabilitation are difficult to achieve.

Prisoners in Phuket are locked into their dormitories from 6pm to 6am. The major expense, says Commander Rapin, is 1.3 to 1.5 million baht a month for food.

There are 80 or 90 ladyboys among the inmates, and we saw one prisoner today who preferred a negligee to shorts.

We watched as the inmates filed out of their dormitories and were patted down on the way. The three largest sleeping quarters are shared by 252, 229 and 230 people.

Nothing appeared to be left to chance during today's dawn raid, involving about 120 police and authorities from the outside.

But if there are ''Mr Bigs'' controlling their drugs empires from inside Phuket Prison, then their smartphones were tucked away today.

It's worth remembering, too, that some of these inmates are in theory innocent men, awaiting trial, but treated the same as those who have been found guilty and sentenced.