The FTSE 100 Index struggled for direction as sliding oil prices pushed heavyweights such as BP and Royal Dutch Shell lower but delivered more cheer for travel stocks.

London's top-flight was flat, ending the day just 0.8 points lower at 6722.6, as Opec's decision not to cut production rippled through markets for a second day.

The announcement had pushed the price of a barrel of Brent crude sharply lower to near 71 US dollars though it steadied at above 72 dollars as the final session of the week drew to a close.

BP was down 6p to 420.2p while Royal Dutch Shell drifted 42.5p to 2223p. Oil and gas exploration firm BG was the biggest faller, down nine per cent, or 86.5p, to 900.2p, while rival Tullow Oil dropped 38.9p, or eight per cent to 426p.

In travel stocks, cruise ship operator Carnival was buoyed five per cent, or 123p, to 2820p.

Thomson owner TUI Travel rose 11.4p to 444.7p and FTSE 250 rival Thomas Cook shrugged off the recent departure of boss Harriet Green as it recovered 2.6p to 121.8p.

Meanwhile, easyJet gained 20p to 1653p but British Airways owner International Airlines Group, a riser in the previous session on the Opec decision, failed to make any further gains, instead edging 0.3p lower to 457.5p.

Analysts calculated that airlines which have already taken positions on oil for years ahead may have to wait to see benefits from the oil price drop.

In currency markets, the pound took another tumble with the likelihood of petrol prices tumbling still further seen as driving down inflation and pushing the likelihood of any interest rate rise even further back.

Sterling fell by a cent against the greenback at just above 1.56 US dollars and was also lower against the single currency at a little below 1.26 euros.

In London, Vodafone rose 6.6p to 234p after comments by Indian government officials that the country may not challenge a Mumbai High Court order against a £312 million tax ruling in favour of the telecoms giant.

A number of retail stocks rose as so-called Black Friday discounting gripped the high street, with Sports Direct International up 16.5p to 660.5p, Marks & Spencer 6.5p higher at 488.5p.

Primark owner Associated British Foods climbed 35p to 3203p while in the FTSE 250 Index, Argos parent Home Retail Group lifted 6p to 200.4p.

IG analyst Alastair McCaig said: "The feeding frenzy that appears to be happening in shopping malls up and down the country should ensure festive sales for the retail sector get off to a flying start."

The biggest risers in the FTSE 100 Index were Carnival up 123p to 2820p, Kingfisher up 10.3p to 312p, and St James's Place up 24p to 794p. Biggest fallers in the FTSE 100 Index were BG Group, down 86.5p to 900.2p and Tullow Oil down 38.9p to 426p.