The number of suspected illegal immigrants being handled by a Dover holding centre has fallen by 77%.

Between July and December last year 1,886 people were temporarily detained at the site at Dover Eastern Docks.

The centre is specifically for migrants who have tried to get into UK covertly, usually in vehicles but sometimes in small boats or via the Channel Tunnel.

This compares with 8,164 in the same six months of 2015, watchdogs say. It is the equivalent of reducing from an average of 44 a day to 10.

In addition 128 people were detained for more than 24 hours in that second half of 2016 compared with 1,011 in the same period of 2015.

The findings are in the first annual report by the Dover Independent Monitoring Board (IMB), part of the wider IMB that oversees the treatment of inmates in prisons, immigration removal centres and short-term detention sites.

The group was satisfied with the treatment of those at the Dover centre but wants a prompt upgrading and expansion of it to make it more suitable for holding detainees for up to 24 hours.

It also wants to see more protection for potential victims of traffickers.

Peter Finnimore, chairman of the Dover IMB, said: “In 2016 the number of detainees passing through the holding room fell steadily, probably due to improved security around Calais port and the Channel Tunnel.

“The board is concerned, however, about some people passing through the facility, mainly young women, who might be victims of trafficking.

“It believes ministers should review the procedures to take further steps to protect vulnerable people.”

Since beginning monitoring in March last year, IMB members have found that Dover detention custody officers consistently treated detainees with care and respect.

There were no apparent cases where force was used to restrain detainees.

Immigration officers involved in interviews and investigations also showed care and respect and tried to minimise the length of time detainees had to spend in the holding room.

But the IMB said that because of the very limited facilities at Dover, detention over 24 hours should be exceptional.

The local IMB was appointed in December 2015 by then-Immigration minister James Brokenshire.

This was to monitor the short-term holding of suspected illegal immigrants at the Eastern Docks.

In 2015 the centre was unable to cope with an unprecedented wave of migrants trying to get into the UK.

That summer had seen Kent’s roads gridlocked by the combined havoc of French strikers’ blockades and migrants trying to break into the backs of held-up lorries at Calais or get through the Channel Tunnel.

The centre at Dover Eastern Docks is a large room that can take up to 58 detainees and a small separate room for families.

It is the first at a seaport, because of its closeness to the Continent, while similar centres are in airports.

Migrants suspected of being in the UK illegally, including overstaying their time here, are sometimes brought to the centre following arrest by immigration enforcement officers or police.

Here, they are fingerprinted and interviewed.

Many detainees are temporarily allowed in the country for their asylum claims to be assessed.

Those who can be detained for longer and taken to an immigration removal centre, although the one at Dover Western Heights closed in November 2015.