The Commodity Futures Trading Commission is investigating new allegations involving the same individuals who last year defaulted on delivery of Maine potatoes to fulfill contracts traded on the New York Mercantile Exchange to see if any price manipulations are talking place.

Specially, the CFTC is looking at two press reports originating from Simtag Farms last week. Simtag is a large potato growing operation in the Pacific Northwest owned jointly by Jack R. Simplot and Peter J. Taggeres, the two individuals primarily involved in the celebrated potato default.

The first report last Wednesday, which apparently was confirmed by Taggares, said Simtag had agreed to sell 150,000 long tons of potatoes to a European importer. The folowing morning, Taggares, in a clarification, said the amount sold was actually only 15,000 tons, with the larger figure referring to what was possible in the future.

Between the two reports, the price of potato futures rose sharpely, and dropped steeply when the clarification was received.

According to trade sources, Taggares was actively involved in Maine potato futures trading during both the price runup and the subsequent drop, and holds a sizeable "short" position of about 3,000 contracts. That means he is committed to come up with 50,000 pounds of Maine potatoes for each contract he is short when the contracts he is short when he contracts expire - a situation reminiscent of the one that led to the 1976 default.

It is not believed, however, that Simplot is involved in futures trading at present.

"The allegations were made and conversations are under way" with the New York Mercantile Exchange, according to CFTC chairman William T. Bagley who would confirm the inquiry but would not give specific details other than to say that his regualatory agency first heard about the situation in a telephone call from officials of the Merc last week.

"The basic fact is we are on top of the situation and aware of the problem," said Bagley. "We have alerted our enforcement people and they are on top of it."

New York Merc persident Richard Levine would only say that his "exchange is involved in market surveillance on a constant basis" and was loking to see whether the discrepancy in the two reports could be "nothing more than an honest error."

Taggers and Simplot could not be reached for comment.

The five-man CFTC, which watches over future trading and was embarrassed when last year's default seemed to catch it napping, is supposed to get a preliminary report on the current situation Tuesday morning, a CFTC spokesman indicated.

A full report on what happened in the 1976 potato futures trading debacle has not yet been completed and is now expected about March 31 when it is probable the CFTC also will file a complaint against those who it decides were responsible.

In the current situation, the first press dispatch reported last Wednesday by Reuter - the wire service which closely monitors commodity activities - said that Simtag farms had "reached a final agreement with a European importer to sell approximately 3 million hundredweight (150,000 long tons) of Northwest potatoes," and that Taggares, reached by phone, "confirmed trade reports " of the sale.

The following morning, more than an hour after trading had commenced on the New York Merc, Reuter ran a dispatch headlined, "Simtag Clarifies Report of Potato Sales to Europe," which reduced the amount actually sold to only one-tenth of the original report.

"Asked to clarify his confirmation of a report that Simtag would supply 3 million hundredweight (150,000 long tons) to the European importer, Taggares told Reuters that the large figure referred to the amount of business that could be secured . . . in the event that supply problems develop with the Maine potato crop," according to the dispatch.

Trading in the May deliverp potato contract on the Merc that Thursday morning ran to the price up to $10.60 per hundredweight before the clarification came out. The market had closed at $10.19 the day before. After the clarification, the price on the May contract dropped back to $10.03, but rallied a bit to close the day at $10.10, off 9 per cents for the day.