The FTSE 100 Index broke the 4600 barrier yesterday in a session of contrasting fortunes for two of the UK's largest retailers.

Tesco was the subject of a spending spree by investors after it announced half-year profits of £822m, which one analyst described as truly astonishing.

This helped to spur the Footsie to close at a two-year high, up 28.9 at 4608.4, and offset further disappointment at Marks & Spen-cer, where sales continued to slide.

The US Federal Reserve, which is expected to announce that interest rates are to rise by a quarter point, is likely to set the direction of the London market today.

The Dow Jones Industrial Average struggled for momentum early on as traders kept their powder dry ahead of the rates decision, but was still camped in positive territory with a gain of ten points.

Tesco was the top riser among blue-chip stocks in London, up more than three per cent, or 9p, to 285p, after revealing that profits had risen 24 per cent in the first half and that it continued to attract customers from its rivals.

It was followed by Shell, as investors looked forward to today's strategy presentation by the oil group. Shares were up two per cent, or 9p, at 432p.

Shell and rival BP were also benefiting from continuing strength in the cost of a barrel of US light crude, which remained above $46 in New York. BP shares climbed 9p to 538p.

The UK's largest pubs group, Enterprise Inns, moved 1p higher to 590p after saying that trading was comfortably in line with expectations.

It also announced the departure of the managing director of Unique Pub Company, which was acquired by Enterprise earlier this year.

Marks & Spencer was in the red, weakening 4p to 341p, after saying clothing sales during the summer had been difficult.

The trading update came as the company said shareholders could get ten per cent more than the retailer's current share price from its £2.3bn share buyback.

Rival Sainsbury's was also in the doldrums, weakening 2p to 272p, while Boots retreated 16p to 663p.

Media stocks were weighing the market down, with WPP falling 3p to 519p and ITV off 2p at 110p.

Newcomer Cairn Energy was also in negative territory on its second day in the Footsie, falling 15p to 1500p.

Outside the top flight, troubled nuclear power group British Energy dipped more than 11 per cent, or 2p, to 19p, despite speculation that it would receive European Commission approval today for its debt restructuring deal.

Two of the day's best performers were BHP Billiton, which was up 11p at 562p, and Barclays, which climbed 10p to reach 541p by the close