In mounting trouble, Morocco King may soon call for US help

Morocco is shaping up as the next ''moderate'' Arab country in North Africa making a bid for extra US help to ward off the designs of Libyan leader Muammar Qaddafi.

King Hassan of Morocco is in mounting trouble and his parliament has already pointed the finger at Libya and Algeria as likely sources of some of his woes.

He has sent messages to President Reagan and a handful of other key world leaders calling their attention to this alleged outside interference. The US State Department had already voiced its concern at the escalation in hostilities.

The growing challenges to King Hassan:

* An apparent resumption of the war over the Western Sahara, in which inhabitants of that territory are challenging the assumption of Moroccan sovereignty over it after Spain's withdrawal in the mid-1970s.

* A simultaneous stepping-up of the level of weaponry in use against the Moroccans in that war - including surface-to-air missiles and tanks. What was perhaps the biggest battle in the conflict occurred last week around the Moroccan garrison town of Guelta Zemmur.

* The breakdown within Morocco of the national consensus behind the King's policy on Western Sahara. Late last month four opposition socialist leaders were sentenced to one-year jail terms - basically for having criticized him.

* A worsening social and economic situation, which burst into open protest demonstrations last June 20 in Casablanca.

* A change of French policy toward the two major countries of northwest Africa following President Giscard d'Estaing's defeat by Socialist Francois Mitterrand. The former had tilted toward Morocco in the longstanding rivalry between Morocco and Algeria. Mitterrand tilts toward Algeria.

(The US still tilts toward Morocco, despite Algerian help at the turn of the year in freeing the US hostages held in Iran.)

There are still unanswered questions about the resumption of hostilities over the Western Sahara. In effect, the new warfare would seem to wreck hope of implementation of the compromise plan worked out by King Hassan during the summer with the Organization of African Unity (OAU) for a referendum in Western Sahara to confirm - or otherwise - Moroccan sovereignty.

What is not clear is who might want to ditch the plan by stirring things up.

Is it King Hassan, in a mounting sea of troubles, who sees in a resumption of hostilities the basis for: (1) a claim on US help against Colonel Qaddafi; and ( 2) rebuilding the national consensus at home, broken by socialist criticism of royal ''weakness'' in ever agreeing to a referendum?

Or is it Polisario, the Western Sahara guerrilla organization, with its own government-in-exile, which has come to the conclusion that King Hassan's referendum proposal is a maneuver?

A Polisario spokesman emphasized on Havana Radio this month that his organization insisted on independence for Western Sahara under the name of the ''Saharan Arab Democratic Republic.'' They wanted to achieve it by negotiation and peaceful means. But if Moroccan ''intransigence'' prevented this, ''a solution will have to be achieved on the battlefield.''

On the ground in Western Sahara, the Moroccan Army has secured for itself the so-called ''useful triangle'' bounded by El Aiun (the capital), Semara, and Bu Craa (site of valuable phosphate deposits). Most of the rest of the sparsely populated territory is virtually a desert no man's land.

As for King Hassan's manipulation of the situation, there is little doubt that he did his utmost to convey to the outside world (and the US in particular) that the surface-to-air missiles that shot down two Moroccan planes were either installed or operated by non-Africans. Clearly he wanted the inference drawn that Cubans, Russians, or other Soviet-bloc personnel were involved. Moroccans suspect that the missiles and the tanks used at Guelta Zemmur must have been paid for by the oil-rich Libyans.

Behind all this is maneuvering involving all four northwest African states.

King Hassan accuses Mauritania of helping Polisario in the latest hostilities and has admitted Moroccan bombing of Polisario positions allegedly inside Mauritania.

Morocco has in the past correctly accused Libya and Algeria of supporting Polisario. But in the summer there was a surprise rapprochement between Morocco and Libya. King Hassan apparently hoped Qaddafi would thereafter stop his arms supplies to Polisario. Qaddafi counted on Morocco's being more sympathetic toward Libya's presence in Chad and Qaddafi's presidency of the OAU next year. That now seems to be coming unstuck.