A federal appeals court said Monday it needs more time to consider whether to block Whole Foods Market Inc. (WFMI) from buying Wild Oats Markets Inc. (OATS).

The U.S. Court of Appeals for the D.C. Circuit temporarily put the deal on hold until it can hear more arguments although the three-judge panel said the decision "should not be construed in any way as a ruling on the merits" of the case.

The Federal Trade Commission on Friday asked the court to stay a decision Thursday by U.S. District Judge Paul L. Friedman that allowed the transaction to proceed. The agency wants to block the deal on antitrust grounds.

The panel ordered the FTC to explain by Wednesday afternoon why it appealed. Whole Foods will have until Thursday to respond. The accelerated schedule suggests the court plans to move quickly.

Whole Foods is blocked "from taking any further steps to acquire the stocks, assets or any other interest" in Wild Oats until the judges issue a further ruling.

Shares of Whole Foods fell $1.15, or 2.6%, to $43.19 Monday, while shares of Wild Oats fell 7 cents to $17.85.