National Highways has withdrawn claims the deaths of thousands of trees beside a new road might have been due to government pressure to open it early.
Many trees died soon after they were planted alongside the 12-mile (19km) section of the A14 in Cambridgeshire.
A National Highways project manager told a council meeting 850,000 trees were planted out of season after Number 10's intervention.
The company has now apologised, saying there was no request to open early.
The A14 upgrade was a huge national infrastructure project costing £1.5bn, with the section south of Huntingdon opening in December 2019, a year earlier than planned.
In 2021 it was revealed many of the trees along the route were dying.
Surveys were carried out, and in March 2023 National Highways, the government company responsible for major roads, committed to replanting the dead trees.
Martin Edwards, senior project manager at National Highways, gave a progress update at a meeting of Huntingdonshire District Council's overview and scrutiny committee on Thursday.
'Number 10 request'
He said planting of the original trees and plants took place in the spring, which was not an optimal time.
This was because "during construction time there was a request from Number 10 that the road was opened early", he said.
Hot summers were also blamed for the death of the trees.
Work to replant the dead trees has started and is due to take place over the next few months.
Mr Edwards said lessons learnt from the A14 would be used in future projects, such as the A428 and A66 upgrades.
In a statement issued on Friday afternoon, National Highways said: "The A14 Cambridge to Huntingdon improvement scheme opened early because the construction work was complete.
"It was always our aim to finish the work early to minimise disruption to travelling motorists and the local community, so they can feel the benefits of the upgrade as soon as possible.
"There was no request from government or Number 10 that the road open early. We apologise that this suggestion was made at yesterday's Huntingdonshire District Council meeting.
"All trees on the A14 Cambridge to Huntingdon improvement scheme were planted at the appropriate time of year. There is no link between the failure rate and when the upgrade opened.
"There were several factors behind the failure rate including the weather, maintenance and species of trees planted. All of which National Highways is rectifying in our ongoing replanting programme."