Nuclear reactors older than 40 years may need to shut down following Europe-wide stress tests due to extra safety costs.
"I think there will be a few reactors where decisions are really challenged. In the end it will be a strictly economic decision," Ron Cameron told Reuters.
Europe's regulators ordered region-wide stress tests on nuclear plants following Japan's Fukushima crisis, which include testing the impact of an airline crash, an element which was left out in tests carried out in the U.S.
"It is the addition of the aircraft factor that has made the tests much more challenging."
Preliminary results of the national tests are expected to be published this week.
Slovakia said this week its initial tests showed the country's two nuclear plants are safe and reliable.
Britain is one of the few European countries with an ambitious nuclear new build programme, with six new reactors planned by 2025.
EDF Energy , the UK subsidiary of the French energy giant, plans to build four new reactors in the UK, the first of which was initially planned to start operating in 2018.
But Fukushima has pushed back the timetable due to regulatory delay and Cameron believes even a 2020 start-up date for EDF Energy's first new nuclear plant is difficult.
"2025 is possible, but it seems difficult to us to see how it would reach 2020," he said.
EDF Energy said it will announce its revised start date this autumn.
Fukushima has also thrown up concerns about back-up power supply at power plants, the failure of which was the main reason for the contained reactor meltdown in Japan.
Additional costs for ensuring emergency power supply is likely to add 5-10 per cent to the construction bill of new nuclear plants, Cameron said.
"Private investors will weigh up those factors and you can maybe see some reluctance in the first phase," he said.
Utilities are expected to provide the funding for the initial phase of nuclear new build in Europe, he said, but once the first nuclear stations are on stream private investors will follow.