Trans World Airlines, rather than the national airlines of Egypt or Israel, is expected to provide air service between Cairo and Tel Aviv when the route is opened next year, according to airline industry sources. TWA already serves both capitals and flew between them before air links were cut.

The decision to have TWA, an American carrier, resume the route was described by a TWA official as "probable" and by other sources as definite. It is reportedly based on security considerations, but it might also help Egyptair, Egypt's stateowned airline, retain its lucrative routes to other Arab capitals.

The Egyptians, increasingly isolated from the Arab world because of an economic and political boycott imposed by Arabs opposed to the peace treaty with Israel, are trying to avert a further shutdown of air service between here and other Arab cities.

Iraq, Syria and Libya have already pulled their airlines out of Egypt and closed their airports to Egyptair. Last week a regional Arab aviation conference called on other Arab states to do the same.

Meeting in Tunis, the Arab Civil Aviation Council, an arm of the Arab League, voted to close its members' air space to Egyptian airliners and halt service to Egypt. No date was set for the break, and informed officials said it probably would not occur until the decision was ratified at a special Arab League meeting.

Airline officials here said that a total break of air links to Cairo is unlikely because Cairo is a profitable stop, prominent persons in other Arab countries would be inconvenienced, and the countries dependent on Egyptian labor might be reluctant to make such a move.

In addition, they argue, a cutoff of airline service would be incompatible with the Arab boycott resolutions saying that their actions against the Egyptian government should not harm individual Egyptians.

Several Arab airlines are resisting the cutoff move for economic reasons. Except for the Beirut-based Middle East Airlines, however, they are stateowned and may not be able to hold out against government decisions taken for political reasons. Airline officials said the impetus for cutting air links might be lessened if TWA, rather than El Al Israel Airlines and Egyptair, were flying the Cairo-Tel Aviv routes.

The chairman of Kuwait Airways, Ghassan Nessef, told a Kuwaiti newspaper that his airline would not drop its Cairo service even if Egyptair began service to Tel Aviv. He said his airline was in business to make money and seats on its new Boeing 747 flights from Kuwait to London via Cairo are booked until the end of June.

"Egyptians working here and tourists have not committed any sin to be punished by the suspension of Kuwait Airways flights to Egypt," he was quoted as saying.

The Tunis decision provoked speculation and uncertainty about the future of air service here that the government is seeking to combat. An official announcement yesterday reiterated that no regular air service to Israel is to begin for 15 months, even though the air corridor from Tel Aviv is to be officially reopened when Prime Minister Menachem Begin visits Cairo at the end of May.

Egypt's official Middle East News Agency reported that managers of Arab airline offices here met with Egyptair officials and assured them service would continue, and those airlines still operating here are booking normally. The traffic manager for one of the Arab carriers said, however, that service could be interrupted at any time, and he said he expected it would be.

Egyptian sensitivity over the issue is such that a B'nai B'rith group coming here from Israel was denied permission to fly directly in a chartered plane and was obliged to go through Athens.

The possibility of losing traffic rights to Arab capitals comes at a bad time for Egyptair, which has just embarked on a major expansion of its fleet. The airline has agreed to buy three of the Franco-German wide-bodies airbus jets, and is seeking financing to purchase two Douglas DC10s that would be used to begin service to New York.