Eilish McColgan took an astonishing six seconds off her own Scottish 3000 metres steeplechase record at last night's Diamond League meeting in Oslo to secure the qualifying mark for the forthcoming Olympic Games.

The 21-year-old from Dundee took advantage of a high-quality field to run 9min. 38.45sec. and achieve UK Athletics A standard for London, finishing ninth behind Kenya's Milcah Chemos.

It moved McColgan into fourth place in the all-time UK rankings and eased the pressure ahead of this month's trials in Birmingham where a top-two finish will now guarantee her an Olympic spot.

Fellow Scot Steph Twell secured a B qualifying standard in the 1500m, running a season's-best 4:07.49.

The Commonwealth Games bronze medallist, a late entrant in the Norwegian capital, was stranded at the back in a slow race and ended up ninth with Ethiopian Adeba Aregawi claiming victory.

Lasswade's Guy Learmonth ran an 800m best of 1:47.14, inside the UKA standard for the European Championships, coming second to Gareth Warburton, who set a Welsh record.

Usain Bolt eased to another 100m victory in Oslo but there was disappointment for the British contingent as both Mark Lewis-Francis and Jessica Ennis were disqualified from their races for false starts.

The Jamaican, with typical showmanship, had earlier arrived at the stadium in a faux-vintage dragster with sparks flying out of the back, and he did not disappoint on the track.

Bolt finished in a time of 9.79sec to edge out Asafa Powell, who recorded a season's best time of 9.85.

Lewis-Francis missed out on the race after a false start.

That came shortly after Ennis, who had finished third in her heat, was disqualified from the 100m hurdles for the same offence.

Australian Sally Pearson took the victory in a time of 12.49 ahead of American Kristi Catlin and Britain's Tiffany Porter.

Dai Greene could only manage fourth in the 400m hurdles with a time of 48.98, having coming in to the event off the back of an illness, with Javier Culson cruising to victory in 47.94 – the fastest time of the year.

Abiodun Oyepitan finished second to Murielle Ahoure in the women's 200m in a time of 22.71 but was unimpressed. "I always want to win," she said. "I could have gone harder."

*Andy Frost's hopes of snatching an Olympic place have been ended after the hammer thrower was ruled out of London through injury, writes Mark Woods.

The 31-year-old Scot underwent knee surgery yesterday, having aggravated an existing problem before last weekend's Scottish Championships.

Frost, who is ranked fourth in the UK this year, will be out for at least three months, ruling him out of both the Olympics and European Championships.

"It's very disappointing for him," said Alan Bertram, his coach. "He had surgery in 2008 and they've now had to go in and clean it up again, and with all the rehab, the Olympics are out."