Cops admit they have failed to find any evidence

The remarks by the Metropolitan Police's Andy Hayman came as doubts over whether two British Muslim men arrested in Friday's dawn raid, including one who was wounded, were involved in any terrorist plot.

"We have not found what we went in there to look for," said Hayman who declined to comment on reports they were looking for chemical or biological weapons.

However, Hayman told a press conference in London that the search still had several days to run and was still very much a live investigation.

The senior officer revealed that documents and computers had been recovered from the house, which he described as "material consistent with a search of this nature."