Lebanon's foreign minister today described as an Israeli political ploy the claim by cashiered Lebanese Army major Saad Haddad that he has assumed control of southern Lebanon. The minister also charged that Israel had sought to block the Lebanese Army from extending its authority to East Beirut.

Elie Salem made the statements after Israeli forces tried to drive past a new Lebanese Army checkpoint in the predominantly Christian eastern half of the capital. No shots were fired, but the incident highlighted frictions between the Beirut government of President Amin Gemayel and Israel's occupying Army.

Speaking to a press conference, Salem dismissed Haddad's claims that his Israeli-backed militia now runs southern Lebanon, noting that Haddad has only about 840 troops, virtually no officers and is dependent on Israel for logistical support.

"Israel is in control of southern Lebanon and it moves the stones as it sees fit," Salem said. "The Haddad issue is part and parcel of the Israeli presence in the south."

Haddad, whose militia had controlled a small area of Lebanon on the Israeli border since 1978, announced Monday that he was expanding his "free Lebanon" enclave north to the port city of Sidon, or about 25 miles south of Beirut. His militia staged a parade in the city of Nabatiyeh, about 35 miles south of the capital, yesterday.

Israeli spokesmen announced then that Lebanese negotiators had agreed to incorporate Haddad's forces into the Lebanese Army.

Salem said those reports were incorrect. "No one can announce in truth to the world that we have solved one problem and left the others hanging," he said of the stalled talks with Israel over the withdrawal of Israeli occupation forces.

In Jerusalem, Reuter reported, a senior Israeli official reiterated: "Our reading of the Lebanese response is that the bottom line for Haddad's forces will be their integration in the Lebanese Army. Haddad, who was in Jerusalem, said the move into Sidon and Nabatiyeh "is not a question of taking over more territory. We all want Lebanon saved. If I am deployed in some place or another, it is a guarantee for the future."

Salem's remarks came a day after the Lebanese government took control of the largely Christian eastern sector of the capital from another of Israel's allies here, the Lebanese Forces Christian militia. The rest of the country is occupied by Syrian, Palestinian or Israeli forces.

Salem said the Lebanese Army had moved into East Beirut despite the objections of the Israelis who argued, he said, that "we should not deploy our troops in East Beirut because this changes the status quo. We said that Israel is not involved in this operation. This is a purely internal matter and that the government of Lebanon must take decisions in areas that should be under its control."

Israeli spokesmen here said they had sought the delay to determine where the Lebanese Army would be deploying and thus to avoid any conflict with Israeli patrols. An official statement by the Israeli Defense Forces said they had previously had an agreement with the Lebanese Army allowing Israeli troops to move "freely in all the areas of East Beirut."

Salem, however, said it was agreed last summer that Lebanese Army troops would deploy in East Beirut and that the move was delayed "for certain reasons"--apparently referring to the delicate negotiations the Lebanese government conducted with the Lebanese Forces Christian militia that had ruled the Christian sector for the past eight years.

But now, Salem said, the Lebanese Army intends to exert control over "every nook and cranny" of East Beirut.

"The Army has instructions to shoot, has instructions to act like an army and not to negotiate with outlaws and every force that will encounter the Army in the greater Beirut area," he said.

The warning did not apply to U.S., French, Italian and British troops in the multinational peace-keeping force. Currently they are deployed almost entirely in West Beirut and the suburbs south of it but the Lebanese have been attempting to get the multinational force to back them in East Beirut.

In the incident this morning on the outskirts of East Beirut, Lebanese sources said an Israeli patrol consisting of a tank and two armored personnel carriers was stopped by the Lebanese Army. After about an hour of arguing, these sources said, an agreement was reached in which the Israelis were permitted to drive 300 yards past the checkpoint and then return and depart.

Reuter quoted security forces as saying a car bomb exploded at a service station in a Christian-controlled suburb of Beirut, killing two people and injuring at least one other. The attack occurred in Antelias, a coastal area on the east side of Beirut that remains in militia hands.