The three junta-led Sahel neighbours jointly announced in January they would leave the 15-member Economic Community of West African States (ECOWAS), which has sought to persuade them to reconsider their decision.
Niger and its military-led neighbours Mali and Burkina Faso signed a confederation treaty on Saturday, signalling an ever-closer alignment between the countries in the insurgency-torn central Sahel.
The Alliance of Sahel States treaty, signed on Saturday, underscored the three countries' determination to turn their backs on the 15-member ECOWAS, which has been urging them to return to democratic rule.
Formalising the treaty to establish a confederation confirms the rejection by Niger, Mali and Burkina Faso of the 15-member Economic Community of West African states (ECOWAS).
The new charter also allows Traore to run for president when the elections take place.
ECOWAS said it was lifting financial and economic sanctions against Guinea and ending restrictions on the recruitment of Malians to professional positions within the bloc's institutions.
The measures to be lifted included the freezing of Niger's assets in ECOWAS central banks and the suspension of financial transactions between ECOWAS states and Niger.
With its reputation at stake, ECOWAS's handling of the latest political upheaval - in Senegal - is being closely watched.
A newly formed collective –- comprising some 40 civil, religious, and professional groups –- outlined a series of upcoming actions including a protest and a strike.
ECOWAS' extraordinary session follows Senegal President Macky Sall's sudden decision to delay elections, just a week after Burkina Faso, Mali and Niger declared they were quitting the bloc.
Article 91 of the bloc's treaty stipulates that member countries remain bound by their obligations for a period of one year after notifying their withdrawal.
Sall cited a dispute between the National Assembly and the Constitutional Court over the rejection of candidates.
Burkina Faso, Mali and Niger were founding members of ECOWAS in 1975
Burkina Faso, Mali and Niger were founding members of ECOWAS in 1975, but the bloc suspended all three and imposed sanctions on them following military coups that overthrew elected civilian governments.
Withdrawal will hit hard given that ECOWAS guarantees visa-free travel and right of settlement and work in member countries. Losing such benefits will cause concern, as will the potential effect on regional trade.
The leaders of the three Sahel nations issued a statement saying it was a "sovereign decision" to leave the Economic Community of West African States "without delay".