British Communist Party leader Gordon McLennan asserted his party's independence and opposed Moscow's move into Afghanistan today, from the rostrum of the Soviet Communist Party congress.

His reference to Afghanistan, the first since the congress opened Monday, was censored by the official Tass news agency, which carried the full text of his speech but misquoted him.

McLennan was the first West European "Eurocommunist" to address the congress in the Kremlin, and Western sources said he was allowed to deliver his speech in full.

He told delegates: "The independence and sovereignty of each communist party is the essential basis for relations between our parties . . . .

"Differences can and do exist in the communist movement on certain questions including Afghanistan and our views on this question are well known."

The remark, as carried by Tass in its English language version of the text, ran: "Differences can and do exist in the international communist movement on certain questions . . . and our views on these questions are well-known."

Meanwhile, Soviet Agriculture Minister Valentin Mesyats told the congress today that there are "serious shortcomings" in the national production of cereals used as food and fodder.

He issued the warning just one day after a Kremlin spokesman, Leonid Zamyatin, said the U.S. grain embargo imposed last year because of the Soviet intervention in Afghanistan "did not work and failed to attain its goal." Zamyatin told a news conference that "pressure brought against us either with the help of an embargo or in any other form is a useless practice." e

Mesyats, in a major speech, spoke of shortcomings in meat and milk production. Both depend on adequate grain supplies and are believed by Western analysts to indicate the impact of the embargo.

He called for greater work discipline to help meet the goals of the new five-year plan debated yesterday and today before the 5,000 delegates.