(Reuters) - Miner Anglo American Plc said on Wednesday it was in advanced talks to buy fertiliser maker Sirius Minerals for about 386 million pounds as it sets its sights on Britain's biggest mining project.The proposal of 5.5 pence per Sirius share represents a premium of about 34% to Sirius' last close.Sirius is reviewing the North Yorkshire polyhalite project in northern England after scrapping a plan to raise $500 million in a bond sale, delaying the project.Many local people have invested..