Just when South Africa's Information Department scandal was beginning to bore the public - to the great relief of many politicians - news came that fugitive Eschel Rhoodie, the central figure in the scandal, was arrested July 19 in a French resort town.

Rhoodie is wanted here on seven charges of fraud, in connection with activities when he headed South Africa's $72 million covert propaganda campaign that allegedly involved bribery of overseas opinion makers. The Compaign also involved the establishment of numerous front organizations to influence public opinion in favor of South Africa at home and abroad.

It would be naive to think it took four months for South African and French police to locate Rhoodie in Juan-Pines on the French Riviera where he frequented expensive restaurants, nightspots and tennis courts. A warrant for his arrest was issued March 16, and even that came three months after government investigators officially recommended he be charged.

The South African government has been reluctant to prosecute or extradite Rhoodie because it feared that the former information secretary would make good on his threat to reveal more details about secret activities during his heyday as this country's top clandestine diplomatic courier. Rhoodie's information, it was feared, possibly could undermine South Arfica's relations with other countries.

The reasons for his arrest at this time appear to be rooted both in the internal politics of the ruling National Party, which is torn by factional rivalry, and in the personality of Prime Minister Pieter W. Botha.

Botha is under extreme pressure from the right wing of his party. The conservatives are perturbed by his new policy initiatives, which they view as deviations from the party's racial segregationist tenets. The conservatives, led by Minister of Public Works Andries P. Treurnicht, also are upset by Botha's attempts to bring their section of the party under his firm grip.

As long as Botha is seen to be failing to fulfill his election pledge to have clean government by mopping up the scandal and bringing Rhoodie back for trial, he leaves, himself open for attack by conservatives on this issue.

Already, an ultra-right-wing party, the Herstigte Nasionale Party, has made inroads into the National Party's power base. This was demonstrated in a by-election June 6 in the mining town of Randfontein where the National Party candidate won, but with a significantly decreased majority from the 1977 election.

The move to get Rhoodie back also demonstrates Botha's personal dislike of leaving issues unresolved and of failing to meet challenges head-on. It would be out of character for him to allow Rhoodie to hold the threat of more disclosures over his head.

There is another factor that helps explain the arrest of Rhoodie. Botha has been criticized for his handling of the scandal by both its losers - former information minister Cornelius Mulder and former state president John Vorster - and its beneficiaries - opposition politicians. But few can dispute that Botha has emerged so far personally unscathed and in a position of greater political strength.

He has intimidated the press, which first revealed the Information Department's activities, without formally gagging it. He has helped force from public life those known to be responsible for the scandal - Vorster, Mulder, Rhoodie and former intelligence chief Hendrik Van den Bergh.

By stonewalling and ignoring charges he misinformed Parliament, Botha has succeeded in preventing either himself or his Minister of Finance Owen Horwood from being tied to the scandal, thus avoiding having to make good on his promise to call an election if anyone in his Cabinet was implicated.

The confidence Botha now shows contrasts sharply with is position at the beginning of the year when the scandal's disclosures appeared to threaten the tenure of his young administration. That confidence also is reflected in the government's charging of Mulder with contempt of the Commission of Inquiry into the scandal, for refusing to testify before it. Mulder was charged only days after he announced he was forming his own political party.

Mulder's trial begins Wednesday and he has vowed to use the court as a platform to tell "the truth" about the scandal.

The questions remain: How much does Rhoodie know and dare to say? Disclosure of state secrets would make him liable for more serious charges under South Africa's official secrets act.

If substantiated, allegations that the South African government financed moderate political groups in neighboring Namibia (South West Africa) and Zimbabwe-Rhodesia would harm Pretoria's interests there. There are also claim that bribes were paid to foreign politicians and trade union leaders and that illegal campaign contributions were made to U.S. politicians.

But in all the potential revelations, it appears that direct implication of Botha could come only if Rhoodie has proof that Botha knew exactly why $11.5 million was transferred from his special defense account in 1974, when he was minister of defense. It allegedly was given to Michigan publisher John McGoff to help him attempt to buy the Washington Star newspaper, although McGoff has denied the reports. CAPTION: Picture, Prime Minister Pieter Botha apparently wants to meet Eschel Rhoodie's challenge head-