Coventry Council's leader has said the city should have been consulted over plans to redevelop a playground built in memory of Aberfan disaster victims.
The city of Coventry raised money for the memorial park
The English city raised £4,000 to build Coventry Playground, in Merthyr Vale, following the 1966 disaster in which 116 children and 28 adults died.
Merthyr Tydfil Council is considering plans to build new homes on the site.
But opposition is mounting and a 400-signature petition has been handed in to Merthyr Council from local parents.
Coventry Council leader, Ken Taylor, told the BBC Wales News website that the city should have been told about any plans for the Coventry Playground site.
He added: "We were concerned as an authority that we didn't have any consultation.
"When we found out what was planned, we were quite disappointed.
"We didn't know what was happening - we just got reports that it may be built over.
"Coventry Council will be contacting Merthyr Council over these plans."
In a statement, Merthyr Council said there had been problems with anti-social behaviour in Coventry Park and that a lasting memorial to the Aberfan victims would form part of any new development.
There are plans to redevelop Coventry Playground
The council stressed that Coventry Playground was not the official memorial, which is sited in nearby Aberfan itself.
The statement read: "Recently, there has been a problem with anti-social behaviour from youths congregating in the Coventry Playground.
"Consequently, the project to re-develop the site has now been identified as part of the regeneration process for the area.
"If approved, the main aim of the scheme will be to provide a development with a lasting memorial or a small play area.
"This would be subject to further consultation.
"Merthyr Council would like to stress that due consideration will be given at all times to those involved and affected by the proposals."
In total, 144 people died in the Aberfan disaster
Coventry leader Mr Taylor said he understood the problems faced by Merthyr Council but added that the site should keep its association with the city.
He said: "There may be a problem - the world has moved on in 40 years - but we would like to see recognition of the people of Coventry in whatever is planned.
"I understand what Merthyr are saying, but my concern is that we were not consulted, bearing in mind it is a Coventry play area.
"It was put in place by public money."
Aberfan, near Merthyr, was devastated on 21 October 1966 after a slagheap overlooking the village became unstable.
Tonnes of waste slid down the mountainside toward the village, hitting Pantglas Junior School, whose children had just returned from their morning assembly.
The slide engulfed the building, killing 116 children and five of their teachers.
The slurry also engulfed 20 houses.
In total, 144 people died.
Conservative councillor Mr Taylor added that he had clear personal memories of the aftermath of the Aberfan disaster from 1966.
At the time he was a member of the Edgware Round Table in north London whose members opened up their homes to Aberfan families whose houses had been destroyed.