THE southbound carriageway of the M1 near Watford remains closed as Highways Agency investigators probe the cause of a fierce blaze at a scrapyard this morning.

Motorists travelling southbound from junction 5 (Watford), will have to exit at junction 4 (Edgware) and follow the diversion signs.

It is still unknown when the southbound carriagway will fully reopen, however there are reports of the closure being in place into the weekend.

The motorway was closed early this morning following a blaze at the scrap yard in Mill Hill Broadway.