Shares in U.K. supermajor BP slid six percent in early Friday trading, as oil industry shares looked to suffer again from “weekend” nerves shown at the height of government financial angst last Friday.

BP shares fell 5.68 percent by mid-morning in London despite news oil output at one of its Azeri platforms was on again after a month of repairs. News agency Reuters reported production would double to 600,000 barrels per day, although 900,000 bpd was normal.

London’s main indices were down up to 5.32 percent before lunch, weighted down by falling energy shares. By mid-afternoon, London's main indices had all fallen by between six and seven percent.

Tullow Oil shares dipped 6.82 percent despite an AFX report from South Africa saying Ghana’s Jubilee field would produce 120,000 bpd in 2010. U.K.-based gas-storage company Portland was down seven percent after reporting investment terms in a flagship project were still being put to “prospective” potential partners.

Venture Production was down 6.5 percent for reporting it would pay E.ON Ruhrgas’s UK business £14.8 million for 14 percent in the Cygnus, Kepler, Copernicus and Humphrey gas discoveries.

Premier Oil shares fell even with a management decision to buy back shares.