As desperately poor and overcrowded as it was at independence, Bangladesh was six years old last weekend, and its military leadership celebrated the occasion with all due pomp and ceremony.

There are signs, however, that many of the old stresses and uncertainties that have plagued the country since it freed itself from Pakistani rule in 1971 are beginning to reassert themselves, ending a recent stretch of relative stability.

Economically, the indicators have begun to turn sour. Inflation, which has not been a recent feature of the economy to any recognizable extent in the cities and villages is creeping up. Now, however, it is running at 15 per cent, and the sounds of grumbling can be heard more and more loudly.

The rice harvest this year was none too good, and international economists see no long term encouragementin the world price of jute, the country's principal export.

Meteorologists note with concern that the past three monsoons that have swept up from the Bay of Bengal have been unusually good: the probability that next year's will be bad - with all the attendant troubles - is very high.

As recently as six months ago, Zia spoke of his determination to return to the barracks and let his country be taken over by civillians once again. Now, he has decided to make a bid for civilian power himself, a decision that has unleashed many of the rival forces that have brought instability to Bangladesh in recent years.

The general's power base in the 75,000-strong army seems no longer as secure as it once was.

Last September, in the midst of an already dramatic hijacking saga taking place on the runway of Dacca airport, a small but apparently determined group of soldiers attempted to stage a coup. For a while they took over the northern town of Bogra and, on Oct. 2, made a brief and bloody attempt to seize power in Dacca itself.

They were repulsed, and some 250 of the ringleaders have since been shot, or hanged, after summary military trials. Some of the generals whose loyalty came into question have been transferred, and as recently as last week, eight air force officers resigned and an army general was forcibly retired.

The whole military structure was shaken to the core, and Zia, who draws his strength from the stability of that structure, has seen his authority dangerously eroded.

For reasons that owe as much to Zia's personal ambition as to his recognition of the risks of retaining his military links indefintely, he has been attempting a cautious flirtation with some of the country's 18 legal political parties.

In a television address to mark the sixth anniversary of independence, Zia announced that he was forming a "political front" to spearhead his attempts to gain broad-based support. Judging from the reaction to the address, however, the leading politicians in Dacca are going to hesitate for a while before joining forces with the general.

Typical was the reaction of Mashiur Rahman, leader of the country's third biggest group, the National Awami Party. "For weeks I have been telling Zia that we would only join him if he agreed to set a firm date for elections, if he agreed that in the democracy he promises there would be a supreme parliament, and not a supreme president, and if he agreed to allow free political debate again," he said.

"But he has done none of these things.He insists on presidential government . He is vague on dates for elections and he won't relax the curbs on the press or on political meetings. So how can we join him?"

Similar reactions have come from other political leaders, leading Western observers to the conclusion that, for the time being at least, Zia may be in serious political trouble.

"The army is in a state of upset, and Zia's lost ground there," said one diplomatic source. "The politicians are suspicious of Zia's entry into politics, and he hasn't gained ground there. He's really in danger of falling between two stools."

As recently as last summer, when Zia held a referendum on his leadership and won a staggering (and widely disbelieved) 90 per cent of the votes, Bangladesh and the government displayed a mood of calm and stability. Now, for a variety of reasons, all has changed. There are many in Bangladesh today who wonder out loud in Zia, either as civilian or soldier, can hold onto the reins until his country's next birthday.