Combined UK, Norwegian, Danish and Dutch output, including UK onshore fields, slid to 5.194 million bpd, down from 5.999 million in July, Wood Mac said in a monthly report.

The losses were centred in Norway where production plunged by 845,000 bpd in August to 2.4 million bpd. This was Norway's lowest monthly output for four years, Wood Mac said.

The switch of the Ekofisk area fields to the new Ekofisk II facilities forced the falls. Overall output from the Ekofisk area and satellite fields decreased from 394,000 bpd in July to just 167,000 bpd in August.

Scheduled maintenance at Norway's Gullfaks C, Statfjord and Sleipner field centres also hit production hard.

The Sleipner field fell by 116,000 bpd to 49,000 bpd. Production rose slightly at the Vigdis and Yme fields, to 98,000 bpd and 41,000 bpd respectively.

UKoil production rose by 36,000 barrels per day (bpd) in August to 2.54 million bpd according to a Wood Mac report earlier this week.