The federal government says the clean-up of affected sites in Ogoniland will begin in August.
Ibrahim Jibril, minister of environment, gave the hint at a press briefing in Abuja on Saturday in readiness for the World Environmental Day to hold June 5.
In April, the hydrocarbon Pollution and Remediation Project (HYPREP) had said the best companies would be chosen from those that participated in the demonstration exercise.
Jibril said 400 contractors indicated interest after an advertisement was made public in April.
He said the federal executive council’s approval of the contractors pre-selected would make the August timeline possible.
“They (HYPREP) are doing their analysis which is completed now and preliminary figures are giving us a figure of about 140 that are pre-qualified,” he said.
“These are the ones that when we finally get the figures we would invite them to submit their financial duty and that process would continue in the whole of June to July; and we hope that by August we should be able to get to the federal executive council (FEC) to give approval for whatever remediation contract that would be given.”
Commenting on funding of the exercise, Jibril said: “About three weeks ago, the board of trustees was able to sign an escrow agreement in presence of the vice president.
“All these are geared towards getting the escrow account to be opened and joint partners, the oil companies and the NNPC (Nigerian National Petroleum Corporation) are now at the last stage of populating their account with the amount that would be used for the cleaning process itself.
“We are on good track and we expect to do the best we can within the framework of what we are doing now.”
The cleanup of Ogoniland was inaugurated in June 2016 by Vice President Yemi Osinbajo.