Several people are missing and others injured after an explosion at a BASF chemical plant in western Germany, the firm said on Monday.

"There was an explosion with several people injured for as-yet undetermined reasons at around 11:30 (0930 GMT) at BASF Ludwigshafen," the firm's hometown around 80 kilometres (50 miles) southwest of Frankfurt, it said in a press release, adding that local residents should remain inside and shut doors and windows.