POSSIBILITIES of a Vietnamised Biafra developing in East Pakistan can no longer be lightly dismissed. The frenzied flight of foreigners from Dacca this week showed how critical the situation had become. The United Nations ordered a complete pullout of its personnel from the tense province. So had the West German, Japanese and Belgian missions. Other countries advised their non- essential nationals to quit.

What emerged from 10 days of political paralysis was the fact that if West Pakistan's Zulfikar Ali Bhutto could play tough, East Pakistan's Mujibur Rahman could play tougher. The Bhutto boycott of the March 3 National Assembly meeting, which touched off the crisis, was perhaps intended only as a warning to the autonomy-prone east wing that it should not take the west for granted.

In the event Bhutto's tactics only added to the east's suspicions and helped harden its attitude. Sheikh Mujib spoke of a "conspiracy" in the west wing, a charge which drew sustenance from the fact that President Yahya Khan, after having played an admirably neutral role so far, had suddenly chosen to act on the advice of Bhutto.

The violence that erupted in the east wing following the postponement of the assembly was less significant than the conclusive manner in which the Awami League showed that it was in a position to run a parallel government in the east. Mujib's call for a shutdown of all activities and then a general strike met with 100% success, He said banks should open for a few hours a day and banks did just that. He said banks should open on a Moslem holiday to pay salaries to government workers, and the banks did so. For several days the police disappeared from East Pakistani cities and Awami League peace patrols took their place .

The civil disobedience movement does not seem to have been launched on a big enough scale though the call has already gone out that citizens should pay no taxes to the present government. But the Awami League has set up liberation committees in all villages. It is clear that the Sheikh has backed with allround action his assertion that "we are the legitimate source of authority in Bangladesh (the land of Bengal)".

Bengali nationalism has reached such a high pitch that what would have been considered sacrilege till very recently happened in the streets of Dacca last week: the burning of portraits of Mohammed Ali Jinnah, the father of Pakistan. This is confrontation between the wings on a scale unprecedented and with unpredictable consequences. President Yahya Khan's imminent visit to Dacca is the one hope that the worst may yet be avoided. Bhutto sowed the wind and Pakistan is reaping the whirlwind.