In a surprise announcement, the New York Futures Exchange and the struggling Amex Commodities Exchange said today that they plan to merge.

It was an abrupt turnaround for the Amex Exchange, which has tried unsuccessfully to gain a foothold in the burgeoning financial futures trading game.

Only last week the Amex exchange which is affiliated with the American Stock Exchange, and the New York Commodity Exchange announced plans to consolidate their financial futures trading operations.

The New York Futures Exchange is a creation of the New York Stock Exchange, he world's largest securitiestrading floor.

NYFE officials had hoped to open the new financial futures exchange by April 1, although it appeared they willnot get the go ahead from the Commodity Futures Trading Commissionin time to meet that date.

The announcement of the NYFEACE merger -- which also would need CFTC approval -- came as a surprise to the New York financial community.

More than once NYFE officials had said they studied the possiblity of a merger and had rejected it. But those officials conceded that they might be willing to merge with the nearly moribund ACE for "non-business" reasons.

But NYFE might have made the decision to merge with ACE on business grounds after all.

Informed sources said NYFE officials were concerned that they would not be granted permission to trade in all the financial futures contracts they want to, because federal regulators are worried that there may be too much trading in some of those contracts already. When they NYFE opens, it hopes to trade futures contracts in treasury bills, treasury bonds and five foreign currencies.

Federal regulators, as well as some participants in the future industry, are worried that there may not be enough treasury bills around to satisfy all those who might want to take delivery of theircontracts. The addition of yet another exchange trading in bills might make the "deliverability" problem worse.

Chicago, which has dominated financial future trading, there was a scare last December that move bills might be demanded than the Treasury would auction.

Under the proposed NYFE-ACE mergerthe New York Futures Exchange would get the rights to trade Amex commodities exchange contracts, while ACE members would get seats on the new New York Exchange.

ACE is authorized to trade futures contracts in 90-day treasury bills, 20 year treasury bonds and Government National Mortgage Association certificates. It has pending applications at the Commodity Futures Trading Commission to add foreign currencies and certificates of deposit.

Officials of the New York Commodity Exchange, which has been hit hard because of restrictions on trading in silver, were unable to be reached for comment on the Amex exchanges sudden change in plans.

Sources said the NYFE submitted a merger proposal Thursday to the ACE board unanimously approved the plan the same day. Neither exchange would reveal financial detail of the proposed merger.

CFTC officials had quietly exploredthe possibilities of a merger between the ACE and the NYFE and Arthur Levitt, chairman of the American Stock Exchange, had taken the lead in trying to find a merger partner for ACE.