LONDON (AP) _ Police are investigating a series of explosive devices and demands for money mailed to Barclays Bank employees in London over the past 16 months, Scotland Yard said Thursday.

One woman was slightly injured by an explosion, news reports said.

Anti-terrorist officers are ``focusing on a small number of home-made devices sent by mail and delivered by hand to addresses in the London area'' since December 1994, Scotland Yard said in a statement.

News reports said the devices had been sent in the name of ``Mardi Gra.'' The Daily Mail said Thursday that in a letter to its offices last week, Mardi Gra claimed to be ``the code name of a small group of Barclays Bank victims who are in the process of reversing the tide of fortune in their favor.''

Most of the 25 Mardi Gra devices were mailed to Barclays branches, officials and customers; others were left in public phone booths or delivered to shops connected with the bank, reports said.

Letters from Mardi Gra demanded cards to permit the withdrawal of thousands of British pounds from Barclays cash machines, according to news reports.

Barclays chairman Andrew Buxton confirmed the bank had received a number of devices, but refused to give further details.

Although ``we give our staff regular warnings about letter bombs and raids and keeping vigilant generally,'' the bank has not informed staff of a specific bombing campaign, he told BBC radio Thursday.

According to news reports, one device exploded while a clerical worker at Barclays' Hampstead branch was opening it, burning her hands. Another device blew up at the Ladbroke Grove branch, temporarily deafening a male employee, reports said.

Barclays PLC is one of Britain's largest banks, with $259 billion in assets.