Teens were attacked during two robberies that police believe are linked.

The first incident happened at 11.50pm last night in Weymouth Drive, Chafford Hundred.

The four teenage victims - a 17-year-old girl and three boys aged 16 - were walking along Weymouth Drive, near to the roundabout junction with Mayflower Road and Lancaster Drive, when they were approached by a group of seven men.

Three of the men had knives, one of which was held against the throat of a 17-year-old boy whilst one of the other 17-year-old boys was placed in a headlock.

The victims were then forced to hand over their mobile phones, wallets and other belonging.

The teens were shaken but not injured.

A short time later at 12.10am today an 18-year-old man was waiting for a taxi near to the Tesco car park on Fleming Road.

He was approached by a group of seven people who demanded he walked to the cashpoint and withdraw money.

The victim refused and was assaulted, knocked to the floor and left with cuts to his lip and eye. During the assault he also had his wallet, phone and headphones stolen.

Det Sgt Tim Littman of Grays CID said: "Given that both robberies involved a group of seven people and how close in time and place they occurred we believe they are linked.

"We not only want to hear from anyone who witnessed either of these incidents but we are keen to hear from anyone who may have seen this group in the area acting suspiciously who could help us identify who they are.

"All of the victims involved in these incidents are just teenagers and have all been left shaken by what happened. Please do the right thing by giving us any information."

Witnesses or anyone with information can contact Grays CID on 101 or Crimestoppers anonymously on 0800 555 111.