(Updates with deal)
LONDON, Nov 29 (Reuters) - North Sea Forties crude differentials edged lower on Friday after a deal falling to a six-year high.
* The grade hit seven-year highs earlier this week.
* Sour Forties has followed a steep rise for the rest of the benchmark setting grades that are sweet and buoyed by new rules on sulphur in shipping fuels set to start in January.
* However, the relative rise of Forties has been stronger than that of the sweet grades.
* In contrast, the price for alternative Russian Urals in northwest Europe cratered this week after rising sharply earlier this month on a tight programme. The differential has fallen more than $3 a barrel since Nov. 20.
* Forties: BP sold to Mercuria at dated Brent plus $1.35 loading Dec. 28-30.
* Forties: Mercuria bid for a cargo at dated Brent plus $1.75 loading Dec. 22-27.
* Brent Blend: Mercuria bid for a cargo at dated Brent plus $1.80 loading Dec. 29-31. (Reporting By Julia Payne; Editing by Kirsten Donovan and Louise Heavens)