(Adds details, background, Paluel 2)
PARIS, Oct 27 (Reuters) - French state-controlled utility EDF has delayed the restart of all four nuclear reactors at its Tricastin nuclear plant until the end of November, said an update on its website on Friday, which did not provide reasons for the delay.
EDF added in a separate note that it had also postponed the restart of its 1,300 MW Paluel 2 nuclear reactor by 2 months to April 15.
The company was not immediately available to comment.
Analysts have raised concerns that France, which depends on nuclear power for more than three-quarters of its electricity needs, could face tight supply this winter due to the prolonged outages of several nuclear reactors.
The Tricastin reactors, which have a combined capacity of 3,600 megawatts, were scheduled to resume production next week. A notice on French power grid operator RTE's website showed all four reactors were now expected to resume on November 28.
The notice said the postponements were linked to an order by the ASN French nuclear watchdog's decision in September to halt the reactors after it found flaws in a canal dyke bordering the plant.
The ASN was not immediately available to comment. It had said in September that the restart of the reactors were subject to its approval.
EDF had said repair works to strengthen a canal dike had started.
The Paluel 2 reactor went offline in May 2015 for its ten-yearly overhaul. But in March 2016, during the maintenance, its steam generator - which weighs more than 450 tonnes - crashed on to the reactor floor during handling, causing extensive damages.
The ASN this week authorised EDF to change the steam generator. (Reporting by Bate Felix; Editing by Sudip Kar-Gupta)