CAPE TOWN, SOUTH AFRICA, FEB. 9 -- Late last year, when the spirit of political reform seemed to be taking hold in the South African government and expectations of change were high, Stoffel van der Merwe, the progressive deputy minister of information and constitutional planning, was asked by a liberal acquaintance to describe his job.

Van der Merwe, generally regarded as the Cabinet's point man on the thorny issue of sharing power with the black majority, replied that he basically saw his role as that of a scout.

Then, after a moment of reflection, van der Merwe told his interlocutor, former Progressive Federal Party leader Frederic van Zyl Slabbert, "You know, sometimes scouts go out and don't come back."

The exchange, recalled by Slabbert, has taken on added significance in the face of increasing concern by antiapartheid activists that the government's much-heralded initiative on constitutional reforms has become dead in the water. The reforms are aimed at bringing the country's 26 million disenfranchised blacks into the mainstream of national politics.

Publicly, President Pieter W. Botha and other leaders of the ruling National Party, maintain that the reform process is still on track and that 1988 will bring more chipping away at the structures of apartheid, the country's system of statutory separation by race.

Over the past decade, there have been relatively significant steps toward modifying apartheid, including integration of sports and public beaches, the scrapping of "immorality" laws against interracial sex, the repeal of the pass laws that governed the movement of blacks and the opening of business opportunities for nonwhites.

However, the momentum of change that followed the National Party's sweeping victories in last May's whites-only parliamentary elections has slowed demonstrably since last November.

At that time, the government released the former chairman of the outlawed African National Congress, Govan Mbeki, and hinted broadly that imprisoned ANC leader Nelson Mandela might also be released, possibly opening the way to power-sharing negotiations.

The government also accepted recommendations for changes in the 1950 Group Areas Act, which segregates residential areas by race, and made overtures toward a proposed multiracial legislature for Natal Province, which was seen as a potential model for nationwide power-sharing.

Since then, harsh restrictions have been placed on Mbeki. Talk of Mandela's possible release has stopped. Botha has reaffirmed his commitment to "group rights" -- a euphemism for segregation of housing and schools -- and van der Merwe's suggestions of the possibility of negotiations even with followers of the ANC and other "radicals" have been muted.

Van der Merwe today denied suggestions that the reform initiative has become stagnant in the face of strong resistance by the right-wing Conservative Party. The Conservatives won enough seats in the May 6 election to become the official opposition party in Parliament. "Things like this go as an ebb and flow. The reform process has not come to a complete standstill. It is nothing like that," van der Merwe said.

He conceded that Mbeki's release and his own public predictions that it could, in turn, lead to Mandela's release and power-sharing negotiations, may have raised unrealistic expectations.

"People tend to expect things to happen overnight, but the capacity of people's ability to digest change is limited," he said.

Moreover, he said, the aftermath of Mbeki's release was not what the government expected. Mbeki, 77, scheduled speaking engagements across the country and became a "rallying point of a radical campaign," van der Merwe said. It was only then that the government put restrictions on him and scaled back some of the rhetoric about Mandela's release and black-white negotiations, the minister said.

He said he expected reform to continue this year in "small steps." When asked if there was any likelihood of Mandela being released in 1988, he replied, "Nothing is impossible, but I wouldn't take bets on that."

Slabbert, head of the liberal think tank, the Institute for Democratic Alternatives for South Africa, said reform was in a "deadlock" and that Botha's government was in a "strategic cul-de-sac."

Slabbert said the police and Army leaders of South Africa's security management system, whom he called "securocrats," stepped in to prevent Mbeki's release from being used as a springboard to power-sharing negotiations.

"The best of the reformers said, 'Let's make a test on Mbeki and see if we can release Mandela,' " Slabbert said. He added, "The best of the securocrats said, 'Let's release Mbeki and then use him to show that Mandela can't be released and that there can't be negotiations.' I think the securocrats won on that one."

"P.W. Botha is not going to talk to the ANC. He'll allow Mandela out to die, but he won't let him out to be a factor," Slabbert said, adding that he does not regard South Africa as being even in a "pre-negotiation phase."

Colin Eglin, the current leader of the Progressive Federal Party, said he was not optimistic about the future of reform.

"If the government intends to move, it is not prepared to move far enough to meet the minimum, legitimate demands of the black majority," Eglin said.