The FTSE 100 was down 70.12 points at 6,412.93, after flirting with positive territory at the open.
Michael Hewson, senior analyst at CMC Markets, said: “After the choppiness of recent days markets have ended the month with a whimper, with traders remaining cautious ahead of the long weekend in the US.”
He said continued uncertainty over Syria and economic data releases on both sides of the Atlantic that were “completely underwhelming” also weighed on sentiment.
A slight softening in oil prices from their recent highs acted as the catalyst for profit taking for investors in BG Group and Royal Dutch Shell. Shell’s shares slipped 29p to 2,087.5p, while BG lost 18p at 1,227p.
Petrofac was another faller, giving up some of the strong gains made off the back of forecast-beating results earlier in the week. The oil services firm went to the bottom of the table, down 38p or 2.7 per cent at 1,385p.
The rebounds worked the other way as well, with Serco finding its way onto the riser’s board with a gain of 9p, to 547.5p. Rival G4S fared even better, up more than 3 per cent after being on the end of a positive note from JP Morgan. The broker added its approval to the company’s announcement earlier this week that it would strengthen its balance sheet, which had already helped the shares. They added a further 8.5p, to 260p.
Luxury fashion retailer Burberry was also higher, catching a positive tail wind good updates by continental rivals Hermes and L’Oreal. The shares added 4p, to 1,534p.