Virtually every party in the worldwide Socialist International has welcomed Nicaragua's election plans, according to a prominent British Labour Party member of parliament.
Stuart Holland, the Labour Party's shadow minister for overseas development and cooperation, is convinced that most Americans are unaware of how strong the opposition is in Western Europe to the Reagan administration's policies toward Central America and toward Nicaragua in particular.
Dr. Holland, an economist, is returning to Britain this week following a one-week visit to Nicaragua during which he attended celebrations marking the 50 th anniversary of the assassination of the Nicaraguan revolutionary hero, Augusto Sandino. It was during these celebrations that the leftist-led Nicaraguan government announced that elections would be held on Nov. 4. Representatives of the British Liberal and Social Democratic parties attended the celebrations together with him.
Holland said in an interview that the representatives from the three British political parties were unanimous - along the same lines as the Socialist International (SI) representatives - in calling for a halt to United States support for the rebel forces fighting the Sandinistas and for an immediate restoration of Western aid to Nicaragua.
''We all signed a joint press release,'' said Holland. ''But in America, you wouldn't think that any of this happened . . . it just hasn't been reported here.''
Holland said that US State Department officials have been spreading the word that the Socialist International is completely disillusioned with the Sandinistas' leadership of Nicaragua. This is not the case, Holland said, although individual members of the SI have criticized ''mistakes'' made by the Sandinistas in a number of areas.
As examples of such mistakes, Holland cited the Sandinistas' forced resettlement of Miskito Indians and ''ham-fisted treatment'' of Pope John Paul II's visit to Nicaragua.
Holland is the co-author of a 73-page ''counter-report'' on Central America entitled ''Kissinger's Kingdom?'' It results from a fact-finding mission that the authors undertook in Central America in December of last year on the initiative of Neil Kinnock, the Labour Party leader. Mr. Kinnock said during a visit here two weeks ago that US Secretary of State George P. Shultz had told Kinnock's views on Central America and on the deployment of new US missiles in Europe were ''misinformed and misguided.''
Kinnock said at the time that Shultz had gotten ''out of his pram'' - or ''lost his cool'' - after hearing the Labor Party leader criticize US policy toward Nicaragua in the course of an hour-long meeting on Feb. 13. (A pram is a baby carriage.)
The State Department last week gave a cool reception to the announcement that Nicaragua would be accelerating its election schedule. The Department issued a statement saying in part that many important questions remained to be answered, such as who would be eligible to run for office and whether they would have equal access to the news media.
A State Department report on human rights practices in Nicaragua issued earlier this month charged that the Nicaraguan government had harassed opposition political parties, independent labor confederations, the private sector, the Roman Catholic Church, and the independent media. It cited reports from the Nicaraguan Permament Commission for Human Rights which charge that government security forces held many opponents incommunicado indefinitely without formal charges. The State Department said that ''there are credible reports of torture and killing of detained persons by security forces.''
Holland said that based on his own fact-finding trips to Nicaragua he challenged the Nicaraguan human rights commission's allegations concerning torture and killings. He said that when they were questioned concerning such allegations, members of the commission referred to ''psychological torture.'' The deaths, he said, turned out to be deaths which had not been investigated.
Holland contended that the Reagan administration was applying double standards to Central America - one standard for Nicaragua and another for regimes which it supported in El Salvador, Honduras, and Jamaica, for example. He argued that the administration's allegations of an arms buildup in Nicaragua carried out by the Soviet Union and Cuba were misleading and that the Sandinistas did not in any way threaten the United States.
The British parliamentarian said that the CIA-supported guerrillas - the ''contras'' - which were fighting the Sandinistas could not hold territory but had brought about a permament state of siege.
''It's absolutely staggering for a major power to treat a miniscule power in this way,'' said Holland.
Holland said that the US had urged the Sandinistas to bring the election schedule forward. ''Now that it's been brought forward, it's not only not soon enough, it's too soon'' for the administration, Holland said.