The merger between 4-5 Gray's Inn Square and Monckton Chambers has been held up because the sets cannot find suitable new premises.
Tony Wells, chambers dir-ector at 4-5 Gray's Inn, says: "There is one fundamental issue to be dealt with - finding a location.
"However, discussions are ongoing. The issue is being addressed and will be overcome."
The two sets have been expected to announce a full merger for the last two weeks - as revealed on The Lawyer's website on 21 January (www.thelawyer.co.uk).
But a formal confirmation is on hold because of the problem of finding suitable prem-ises to house 75 barristers.
At the time, Monckton's chambers director Alexandrina le Clezio said: "Full discussions between members of chambers are taking place. We expect to make a full ann-ouncement in three weeks."
The delay could last weeks because of the intense competition for space within the Inns and outside.
Wells believes the difficulty in finding suitable premises to house a large merged set is thwarting the plans of other chambers as well as his own.
"Space is a major issue," he says. "There's virtually nothing outside the Inns and very little inside. Strategies are being frustrated by this lack of space."
The principal property outside the Inns under review by chambers is Thanet House, the former home of the Immigration Appeals Tribunal.
But at least four sets are understood to be interested in the building, including One Essex Court and Fountain Court.
Michael Beloff QC, the outgoing head of 4-5 Gray's Inn, has still to decide on a future tenancy. In addition to offers to stay or to join Matrix Chambers, Beloff has received offers from six other leading sets and says he will make a decision at the end of Easter.