A bank robber dubbed the "spelling bee bandit" - because the notes he has passed to clerks contain the same misspelling - is being sought for four robberies in Massachusetts.

The FBI said the man's notes have just one word: "robery" spelt with one B. His latest target was a TD Bank in Peabody, and he is also suspected of raiding banks in Arlington, Reading and Burlington since October 31.

He is described as white, in his late 30s or early 40s, between 5ft 11in and 6ft 2in, and he wears sunglasses and either a baseball hat or hood.

The FBI said it is concerned because the man is becoming increasingly aggressive towards the bank tellers, and a reward is up to 1,000 dollars.