The FTSE 100 Index closed down 42.1 points at 5089.3.
The fallout from Enron's collapse continued to worry investors.
In London, Cable & Wireless slid nearly 8% - down 22¼p to 267¼p - to top the Footsie fallers board.
Mobile phone firm mmO2 was also off 3¼p at 76¼p, while Vodafone was down 4p at 150¼p and FTSE 250 operator Orange slipped 15p to 510p.
Other FTSE 250 fallers were Energis, sliding nearly 4%, or ¾p, to 18¼p, Colt Telecom, off 4¼p at 68½p, and equipment firm Spirent, down 5p at 158p.
Banks also weighed on the market amid sector-wide concern about higher provisions for bad debt.
Abbey National fell 10p to £10.40, HBOS slipped 9½p to 826½p, Royal Bank of Scotland fell 30p to £17.63, Lloyds TSB eased 3p to 757p and Standard Chartered lost 5p to close at 764p.
Northern Rock, which today reported a 18% rise in profits and buoyant lending, also fell, off 5p at 666p.
But with record consumer borrowing figures released for December, retailers were having a good day on the market.
Next rose 10½p to 932½p, Marks & Spencer was up 4p at 374p, GUS gained 2½p to 629p and jeweller Signet was up ¾p at 99¼p.
But it was a bad day for FTSE 350 antiques and paintings dealer Partridge Fine Arts. Shares slid 5%, off 3½p to 61½p, as the London-based group said it had seen a slow start to the year.