The tracked men are said to have trained with extremist outfits linked to al Qaeda and the Taliban and are thought to pose a potential threat to British security.
The dossier of names is expected to be handed over to British anti-terrorist teams soon and is being seen as a big leap forward in the sharing of intelligence between the two countries.
British authorities may wonder why the names were not handed over before the suspects re-entered the UK.
Eleven of the Britons claimed they were studying in Pakistan while seven said they were visiting relatives.
Pakistani security source
We know the number of Britons engaged in what we would call suspicious activities is much higher - probably in the hundreds - but this isn't a Pakistani priority.
One said he was working for a charity with links to Britain and others said they were on holiday.
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