DACCA, June 23. - The capital of East Pakistan is a sullen but pacified city which has seen little trouble in the past few weeks other than sporadic bomb throwing. But outside Dacca and not only in the border regions, the army still faces the almost impossible task of guarding a vulnerable communications system and rural economy against sabotage by the guerrillas of the Mukti Fouj, the Bangla Desh government in exile. The Mukti Fouj still have bases in the interior of the province.

According to diplomatic sources, one base which is yet to prove particularly effective is believed to be situated in the Goapalganj swamp area in the south of Faridpur District. There are also Mukti Fouj in the Madhupur forest reserve almost in the center of the country between Dacca and Mymensingh.

One report indicated that Awami League fighters emerged from the reserve at the end of last week and occupied the small town of Tangail to the south of it, forcing the police to withdraw. The army later re-garrisoned the town.

From all along East Pakistan's 2,500-mile border with India come reports of mining, mortaring and shelling, particularly from the Feni area southeast of Dacca where the closeness to the border of the road and rail line and the configuration of the border itself give advantages to the Mukti Fouj.

USELESS RAIL LINK

The rail link between Chittagong and Dacca is still largely useless because of the destruction of a major bridge in this area, and even when this bridge is repaired the line will clearly be vulnerable to fresh raids.

Other main trouble spots are in the Jessore area near the Western border and in Sylhet, where two British planters were kidnapped by the guerillas.

All but one or two of the two dozen British planters who were still running plantations in the area have now left on the advice of the British High Commission The prospects for the tea industry, which saves Pakistan a fair amount of foreign exchange now look. even more dismal than they did before.

There have been few, if any, reports of actual engagements between the army and Mukti Fouj. Road mines, grenades and the occasional small ambush, plus mostly unsuccessful demolition attempts on bridges are the basic pattern.

The Pakistan army claims to be largely undisturbed by such pinpricks. But quite apart from their effect all the country's communication system and its economy, the military hospital here, according to one report, is taking in some 40 or 50 casualties a day from the whole province.

There is no confirmation of this figure, which has been received in a roundabout way by a diplomatic source. But even if it is slashed by half or two-thirds it still provides all indication of what is happening.

CURFEW CONTINUES

The curfew though lifted in Dacca, still is in effect, in most for the province's district capitals, particularly in those districts bordering India. In some like Rajshahi the army is dug in in the center of the town.

One recent visitor to Rajshahi, a few miles from the Indian border, said there were three explosions in the three days he was there.

Although one of the explosions was said to have been a mortar shell from the Indian side, troops in that area, the visitor said. were just encountering their first landmines on the roads north of Rajshahi.

Schools remain closed in many towns and virtually all western aid projects are in suspension. Diplomatic sources say that Western technicians have been stopped on the streets in Dacca and warned that it would be dangerous for them to remain

Bengali civil servants still at their posts have received letters urging their non-cooperation with the guerrillas.

Apart from the general damage to the economy, there is the looming problem of famine. Pakistan government statements that there is enough food in the province are correct. Experts say there is approximately two months' supply of food grains in silos and stores around the country. Distribution is the snag. The United States has provided the foreign exchange for the hiring of coastal vessels with crews from other countries, but none of these have yet appeared.

NO ALTERNATIVE

Observers here see no alternative for the government of President Yahya Khan but to continue military occupation and control.

The new police force, largely recruited from Biharis and from West Pakistan, is still only 15,000 strong whereas the province in normal times had a police force of some 35,000, and these are not normal times.

Dacca is, as the government claims, now a quiet city, although a bomb thrown outside the Intercontinental Hotel some days ago narrowly missed a British jute buyer and blew up the car he was about to enter

Dacca is rather too quiet for a Bengal city. There are portraits of President Yahya on sale in the bazaar. But the people appear sulky and drained of emotion.

Unexpectedly they came up to you in public places and tell you where you must go, to Jaganath or Iqbal University halls, to the now razed Hindu shanty-town at Shakhari and so on. Some even make out lists on bits of paper. In Jaganath Hall a small boy points out what could be bloodstains on the steps.

The hostility may now be buried but, as one observer said, it's going to need a miracle to reconcile these people.