The lifeless body of the young woman was found Saturday in the early evening, and "the first impression is that it is not a crime politically motivated", told AFP a source close to investigation under cover of anonymity.
A forensic official also told The Associated Press that Dykes was strangled with a rope.
"Following the death of a British woman in Beirut, we are providing support to the family", a Foreign Office spokesman said.
He confirmed that the victim's name was Rebecca Dykes but could not elaborate on the exact circumstances of her death.
The body of Rebecca Dykes was found on the side of a motorway Saturday, with local sources telling the BBC that the United Kingdom embassy employee had been sexually assaulted and strangled.
In a reaction published by The Independent newspaper, Ms. Dykes' family said they were "devastated".
"We are doing all we can to understand what happened", he added.
He said investigators were looking into reports that Dykes had been sexually assaulted.
A spokesman for the Department for International Development where she worked said: 'Our thoughts are with Becky's family and friends at this very upsetting time.
According to her social media profiles, she was employed by the UK Department for International Development (DFID). Our thoughts are with the family at this hard time'.