Campaigners have criticised the ongoing work at Woodburn Forest while checks are still being carried out on some of the companies involved.
Oil exploration and gas storage firm InfraStrata is pressing ahead with preparatory work on the well site in rural Carrickfergus.
Members of the Stop the Drill group tweeted a letter from DETI, which revealed that it is still considering a request from InfraStrata to have a number of companies added to its licence.
The letter read: “Due diligence by the Department is ongoing and accordingly DETI’s consent to the proposed assignments ... cannot be confirmed until the outcome of DETI’s due diligence processes is known.”
Drilling close to Woodburn Reservoir, which supplies drinking water to thousands of homes across Belfast and Co Antrim, is expected to start in the coming months.
Campaigners have previously expressed concern that chemicals used in the process could contaminate the surrounding water table.
“Due diligence is critical in this situation given that the drill site is in a very sensitive location - that is, in a water catchment,” a spokesperson for Stop the Drill said.
In a statement, DETI indicated that consent for the work being undertaken to date at Woodburn and the matter of assignments in the drill licence are separate matters.
“DETI’s consent to the assignment of any right under the Licence is required before that assignment can take effect, but the terms of a Licence are not designed to interfere with commercial companies’ rights to freedom of contract nor to inhibit the carrying on of activities for which appropriate approvals are in place,” the statement added.
“InfraStrata plc as Licence Operator for PL1/10 wrote to DETI on February 5, 2016 seeking DETI’s written consent to the assignment of various revised interests in Licence PL1/10. Due diligence associated with the assignment process is currently being finalised by DETI officials.
“Next steps are for DETI to notify the Licensees of the outcome and to give effect to the required Deed of Assignment if appropriate.”
Meanwhile, around 200 people attended Stop the Drill’s latest public meeting at Belfast Loughshore Hotel on Thursday April 14.