A shake-up in the leadership of neighboring Burma has reopened a search for a successor to the country's aging strongman and drawn the scrutiny of international narcotics and intelligence officials.

Although details from the closed Burmese society are scarce, diplomats here believe the recent purge of senior government officials stems at least in part from a corruption scandal. Narcotics officials further suspect that the offenses may have included drug trafficking, and the fact that most of the purged figures had military or intelligence connections has stirred speculation about a possible foreign espionage ring.

Regardless of the reasons for the purge, diplomatic reports from the Burmese capital assume that it was ordered by the country's undisputed ruler, Ne Win. The reports also say it has virtually paralyzed Rangoon's defense establishment, with unpredictable consequences for the government's war against a spectrum of rebel groups in the outer reaches of the country.

A poor, mysterious land whose unique brand of socialist government has kept it largely isolated for most of the last 20 years, Burma is the largest opium producer in Southeast Asia. It accounts for more than 85 percent of the crop grown illegally by hill tribesmen and insurgents in the rugged "Golden Triangle" region stretching across the borders of Burma, Thailand and Laos.

Recent developments have led narcotics agents here to conclude that more of the heroin refined from Golden Triangle opium at secret jungle laboratories is moving out through Burma than previously believed.

In Rangoon, the biggest victim of the leadership shake-up has been Brig. Gen. Tin 0o, 55, who had been considered the heir apparent to the 72-year-old Ne Win.

A former chief of the Military Intelligence Service and the National Intelligence Bureau, Tin Oo rose to the number three spot in the ruling Burma Socialist Program Party two years ago and held the position of joint secretary general. He had been close to Ne Win for 30 years after he served as an aide to the former general, who seized power in a coup in 1962.

Government and diplomatic circles in Rangoon were thus surprised by a terse announcement May 18 that Tin Oo had resigned from his parliamentary posts. A separate announcement the same day said Bo Ni, a longtime associate of Tin Oo who also once headed the National Intelligence Bureau, had been suspended as minister of home and religious affairs.

Since then, several other high-ranking military and intelligence officials associated with Tin Oo have been purged, and dozens of other supporters reportedly have dropped from sight. According to diplomatic reports from Rangoon, Tin Oo himself was arrested at his home in late June. He and his key associates are expected to be formally stripped of their posts later this month at a special meeting of the Burmese parliament, the reports said.

Among those forced to resign in the purge have been Thein Aung, a former senior National Intelligence Bureau officer considered loyal to Tin Oo and Bo Ni; Maj. Gen. Tin Sien, a former deputy minister of defense; Brig. Gen. Myo Aung, the Defense Ministry's quartermaster general; and Col. Kan Nyunt, the former director of the Defense Services Intelligence office and a nephew of Tin Oo.

While no clear successor to Ne Win has yet emerged from the shake-up, diplomatic reports from Rangoon now mention Lay Maung, a former foreign minister and National Intelligence Bureau chief, as the leading candidate.

In recent days meanwhile, the purge has shown signs of spreading. The Burmese ambassador to Thailand has been recalled in a move that Thai newspapers said was related to the shake-up in Rangoon, and there were unconfirmed reports that at least two other Burmese diplomats had sought political asylum.

No reasons were given for the downfall of Tin Oo and his associates, but diplomatic reports cited instances of alleged corruption as the source of Ne Win's displeasure. One incident linked the wife of Bo Ni to a gold-smuggling venture. Another controversial event was the extraordinarily lavish wedding of Tin Oo's son in March. The ceremony reportedly made such an ostentatious show of wealth in the chronically poor, austere country that many Burmese were offended.

Since corruption is widely regarded as pervasive in the Burmese bureaucracy, diplomats believe it would take more than simple graft to prompt Ne Win to dismiss his purported successor and associates.

Suspicions of a narcotics connection in the shake-up stem in part from the recent discovery of large-scale trafficking into the country of chemicals used for refining opium and the shipment out of Burma of heroin destined for Europe. According to Thai and western narcotics officials, chemicals essential for heroin production, such as acetic anhydride, have been transported from India overland across northern Burma to laboratories near the border with Thailand. Other deliveries of chemicals have come from China, arranged by Sino-Burmese merchants, the sources said.

In addition, narcotics officials now believe more heroin is being shipped out of Burma than previously suspected. Before, it was assumed that almost all the production for export from the estimated 12 to 14 refineries along the Thai-Burmese border was moving through Thailand, but now it appears that other routes have been established to ship the heroin from Burma.

Narcotics officials believe that the trafficking in both chemicals and heroin through Burma could not proceed without large-scale payoffs. However, they concede that little is known about the drug trade in that country.

What is considered fairly sure, based on aerial reconnaissance, is that the latest poppy harvest in Burma in February yielded as much opium as ever, about 500 to 600 metric tons. In Thailand, however, the opium production was reported down to 35 metric tons from 57 tons last year because of inadequate rainfall, declining opium prices and the success of a crop substitution program. Production from Laos was estimated at about 50 tons.

The vast profits generated by the industry constantly motivate traffickers to find ways around narcotics control efforts. A kilogram (2.2 pounds) of heroin that sells for $4,000 to $5,000 on Thailand's northern border is worth well over $1 million when it reaches the streets in the United States, narcotics officials said.