Steve Williams, of Flat Iron Heritage, contacted his local MP, Lindsay Hoyle, after families were blocked from visiting the Chorley Pals Memorial Site at Serre-les-Puisieux.
He claims they were obstructed by a farmer who owns land near the cemetery.
The BBC tried to contact Jean Louis Legrand but could not get a reply.
To reach the Pals' Battalions memorial at the Sheffield Memorial Park, which is owned by Sheffield City Council, visitors must use an unmade public right of way that crosses land owned Mr Legrand.
The path is owned by the town of Serre whilst the park itself is looked after and maintained by the Commonwealth War Graves Commission (CWGC).
The commission's Director General Victoria Wallace said: "We are very concerned about the situation at Serre, and urge any visitors encountering hostility or harassment to report it to the local authorities.
"We are working with the French government and local authorities to find long-term solutions, but meanwhile we urge caution when visiting, and we ask visitors not to inflame the situation by ignoring the parking restrictions."
The dispute has forced Flat Iron Heritage to cancel visits.
Mr Williams, who has been making an annual trip to the area since 2002, said the situation was getting worse.
He said it has caused a "great deal of distress" to those travelling to visit the graves of loved ones.
Labour MP for Chorley Mr Hoyle has written to Foreign Secretary Boris Johnson asking his department to investigate.
Sheffield Memorial Park
Foreign Secretary Boris Johnson has been asked to investigate claims that soldiers' relatives have been stopped from visiting their graves in France.