This statement follows the regular meeting of the Council of Ministers held on Thursday in the Mauritanian capital.
The deferment was justified by a proposal from the Independent National Electoral Commission (CENI) to reschedule the election date for a better organization of the referendum.
CENI did not give any further details, but the direct cause would be the lack of enthusiasm expressed by voters for electoral complementary census centers opened all over the country.
The CENI has also extended until June 13, the deadline for the closure of these centers, which was originally planned for 7 June.
The planned referendum concerns amendments including, in particular, the abolition of the Senate and the modification of the national flag and anthem.
It was rejected, along with the proposed amendments, by a broad coalition comprising a dozen opposition parties, trade unions and civil society organizations.
The proposed amendments stem from recommendations for a dialogue made in October 2015 between the ruling majority and a section of the opposition.