Israel opened a round of overseas diplomacy yesterday as Foreign Minister Moshe Dayan left for Switzerland and the United States and France Minister Simcha Ehrlch arrived in Johannesburg for the first official visit to South Africa by an Israeli Cabinet minister.

Dayan was to meet in Switzerland with Israel's ambassador in Europe and then go to the United States where he will spend about 10 days speaking in major cities on behalf of the United Jewish Appeal.

As he left Israel, Dayan acknowledged that his trip will be a public relations effort to get backing for Israel's position. He said that the timing of his visit, coming immediately after Egyptian President Anwar Sadat's trip to the United States, "will impel me to present our position."

Ehrlich is to confer with South African officials on economic and political matters. Israel and South Africa have developed closer ties in recent years and are major trade partners.

Meanwhile in Cairo, Egyptian newspapers reported that several leftists opposed to Sadat's peace drive with Israel have been arrested for distributing anti-government leaflets.

Interior Minister Mohamed Ismail was quoted as saying that the leaflets "attempted to sow suspicion and instigate the people."

It was not known how many members of the small National Progressive Coalition Party were arrested or when. No further details were available and leftist leaders were not available for comment.

A number of leftists reportedly were arrested in December for similar activities.

In another development, reliable sources in Lebanon said Syria has moved troop reinforcements to Beirut to tighten up security after the capital was shaken by bomb blasts in the past several days.

Reliable sources said the reinforcements were moved in over the weekend from positions outside the city. Estimates of the number of troops involved varied from 1,200 to 2,000. In all, there are 30,000 Syrian troops in Lebanon as a peace-keeping force.