"The D-day is also decided. We've already agreed and fine-tuned what will be required for the intervention," Musah was quoted as saying by Qatari media.
Although the ECOWAS commissioner refused to disclose the date of possible intervention, he said that the bloc's troops were ready "to go anytime the order is given."
The commissioner added that the African bloc could send a diplomatic mission to Niger on Saturday.
"Tomorrow there is the possibility of an ECOWAS mission going into Niger to continue to pursue the peaceful path to restoration of constitutional order. We are ready to resolve the issue peacefully but it takes two to tango," French media quoted Musah as saying.
Musah made the statement at the end of a two-day meeting of the ECOWAS general staff chiefs in the Ghanaian capital, Accra.