An alleged acid attack near Watford has put a man in hospital.

Police were called to Hilfield Lane, Aldenham, at around 10am on Monday, March 18, after two men in dark clothing with balaclavas covering their faces reportedly approached the victim in his 30s.

An "unknown substance" was thrown towards him, a force spokesperson said, injuring his face and torso.

Update on March 21: police reveal suspects were women armed with knives:

A police spokesperson said: "We have since received further information that the suspects were two women, reportedly in possession of knives, and this line of line of inquiry is being explored."

A social media post believed to have been posted by the victim claims it was "acid", and a picture appears to show one side of his face severely swollen. 

He was taken to hospital for treatment but his injuries are not life-threatening, a Herts Police spokesperson said.

There have not been any arrests and the investigation is ongoing to establish the circumstances around the incident and identify those involved. 

Anyone with information can contact police via non-emergency number 101, quoting reference 41/22287/24.