Sheeran and co-writers John McDaid of Snow Patrol and producer Steven McCutcheon have denied their 2017 track rips off part of the 2015 song Oh Why by Sami Chokri.

Chokri, a grime artist who uses the name Sami Switch, and his co-writer Ross O'Donoghue claim a central "Oh I" hook in Shape of You is "strikingly similar" to an "Oh Why" refrain in their own composition.

But US forensic musicologist Anthony Ricigliano concluded it was "objectively unlikely" that any similarities between the songs "result from copying".

Mr Ricigliano, who was instructed by the Shape Of You co-writers' lawyers but told the High Court he was "completely impartial", said he considered the extent of the alleged similarities between the two songs to be "overstated".

He wrote that "the overall design and musical development of the melodic, harmonic and lyrical content in the relevant phrase in Shape of You are distinctively different from that utilised in Oh Why".

But in contrast, another musicology expert, Christian Siddell, said he found melodic similarities were "so numerous and striking that the possibility of independent creation is... highly improbable".

Sheeran has argued in his written evidence that his song's "Oh I" phrase uses "a basic minor pentatonic pattern" which is "entirely commonplace".

However in court, Mr Siddell, who was instructed by Chokri and O'Donoghue's lawyers but outlined his own professional opinion in his report, said he felt there had been "over emphasis" in relation to references to the minor pentatonic scale in the case, adding: "The Oh I and Oh Why phrases are melodies not scales."

He concluded there were "striking and substantial similarities between certain aspects of the lead vocal melody of Oh Why and Shape Of You".

He said the two melodies were "nearly identical in respect of their rhythm and pitch", the phonetic sounds of the vocal lines were "musically indistinguishable to the ear" and other compositional similarities included the use of "phrase repetition" and "the musical dynamics".

Mr Siddell said that similarities between the two works were "unlikely to be the consequence of coincidence".

Sheeran, McDaid and McCutcheon launched legal proceedings in May 2018, asking the High Court to declare they had not infringed Chokri and O'Donoghue's copyright.

In July 2018, Chokri and O'Donoghue issued their own claim for "copyright infringement, damages and an account of profits in relation to the alleged infringement".

The trial continues, with judgment expected at a later date.