CALCUTTA. - The governing organization of the freedom movement for East Pakistan (Bangla Desh to its supporters) is both visible and invisible here.

The visible portion is its Bangla Desh mission to India in downtown Calcutta.

Since April 18, the mission has been headed by Hossain Ali, former deputy Pakistan high commissioner in Calcutta who is a professional Pakistani Foreign Service officer.

As a Bengali. Mr. Ali's sympathies were with the Bangla Desh (Land of Bengalis) movement from the outset.

He barred non-Bengalis from the building, ran up a new flag, and continued operating without losing one day. But although he heads the large missions Mr. All admits he gets his instructions from a government that has no fixed abode. In short, from an often invisible Bangla Desh regime.

"Mujib Nagar now call be anywhere -- inside East Pakistan or outside," he says. Mujib Nagar means Mujib's capital, a reference to Awami League leader Sheikh Mujibur Rahman who was named in absentia president of the Bangla Desh government while under detention in West Pakistan,

FIVE FORM RULE

Five selected ministers form the government, which keeps on the move most of the time to avoid Pakistani reprisals. It spends some time on Pakistan territory to validate its claim to be on the only legitimate government of 70 million people there.

"Bangla Desh consists of 99.9 percent of villages and towns,'' asserts Mr. Ali,

The government also likes to show itself occasionally in India where between 5 million and 6 million of its people now have fled,

The government is headed by Tajuddin Ahmed, former No. 2 man in Sheikh Mujib's Awami League. He is Bangla Desh's prime Minister in exile.

Acting president during Sheikh Mujib's enforced absence is Nazrul Islam who is technically called vice- president.

These men have no fixed addresses, but they like to make their presence known whenever security permits. If they become too remote from public view, they risk losing their credibility.

What is the Bangla Desh objective? I asked Mr. Ali.

"ONLY ONE POINT"

"Today we have only one point - complete independence from West Pakistan," he answered.

"We no longer follow Mujib's six points." The six points were those Sheikh Mujib set forth in his negotiations with Pakistan President Yahya Khan last March.

"All alien army started total war against our entire people complete with atrocities," Mr. Ali continued. "Now all Bengalis want only independence."

"All Bengalis are motivated now. They want to fight for their freedom," he said. "Pakistan Army retaliates with deliberate atrocities - rape, murder, looting. They destroy villages and all that moves."

Mr. Ali added: "We don't engage them head on with positional battles. We fight hit and run guerrilla warfare with captured equipment. It may take a long time to win by such methods"

He is confident, however, that Bangla Desh freedom fighters are destroying bridges and communications, Little rail service now operates in East Pakistan, he claims. He also believes the Pakistan Army is harassed, demoralized, getting panicky, and afflicted by dissension.

TROUBLE SEEN

The Bangla Desh mission head speaking in an office on a quiet Calcutta side street asserts that West Pakistan is in serious industrial trouble.

"It depends on East Pakistan raw materials - and selling finished goods in East Pakistan, Both its raw materials sold markets are disrupted," Mr. Ali declares.

"We tell the farmers not to plant the jute crop but only food. Jute is money crop for West Pakistan"

Mr. Ali showed photographs of alleged atrocities.

Stories of rape and murder are so common among refugees that it would be difficult to dispute their authenticity Other Bangla Desh objections to the treatment of East Pakistan are that only 8 percent of the armed forces are Bengalis when they make up 56 percent of the population and that only 15 percent of the civil service is from East Pakistan.

INEQUITY ARGUED

Also, the Bangla Desh claims that the bulk of the nation's capital is invested in West not. East Pakistan Moreover East Pakistan declares it produces 80 percent of the country's exports but receives only 20 percent of foreign aid, though now East Pakistan is to get more than half the $1.1 billion in the public-sector Program approved by the National Economic Council .

Mr. Ali feels that economic factors, freedom-fighter pressure. alleged atrocities, and above all the visible evidence of more than 5 million escaping refugees testifies to the soundness of the Bangla Desh case and should influence international opinion in its favor.

"We will go on fighting," he says. "We have no alternative. Our victory would be accelerated if we can get support. Moral support helps of course. But Bangla Desh needs formal recognition too. That would be the answer to those continued crimes against humanity."