A million workers in Poland's industrial heartland staged a warning strike today over food shortages amid an increasingly bitter war of words between the communist authorities and independent Solidarity trade unions.

As tensions increased, officials also revealed that Communist Party leader Stanislaw Kania has been suffering from an illness of an undisclosed nature for the last three days and has canceled public appointments. They said he was resting at home and is expected to resume work soon.

Kania's illness could explain the postponement of an important Communist Party Central Committee meeting originally scheduled for this weekend. The policy-making committee is now scheduled to meet Tuesday to discuss the latest crisis caused by the government decision to cut food rations and the prospect of large price increases.

Despite protracted talks yesterday, the government and Solidarity appeared no closer to finding a way to combat the mounting frustrations of ordinary Poles. Today each side accused the other of blocking a solution by taking an irresponsible approach to the negotiations.

The harshest words came from the government, which, in a statement released through the officials news agency PAP, attacked Solidarity leaders for "unprecedented arrogance" and "insulting behavior." The statement alleged that the Solidarity side had walked out of the talks shortly after midnight after refusing to sign an agreed-upon communique.

A different version of events was provided by the Solidarity spokesman, Janusz Onyskiewicz, at a press conference today. He said the decision not to sign the communique was made after the government attempted to weaken some of the wording on issues such as a commitment to restore full rations in September and Solidarity's access to the news media.

Whatever the rights and wrongs of the dispute, it appeared to herald a new test of wills between the two sides over the extent and pace of economic and political reforms. Many Solidarity activists believe that, despite last month's Communist Party congress, reforms are still being held up by an entrenched bureaucracy fearful for its own position and privileges.

Government officials, meanwhile, emphasize the danger of economic collapse and uncontrollable political tensions unless there is an immediate improvement in productivity and a halt to strikes and street demonstrations.

Some political analysts believe that the present stalemate probably will continue until at least the last week in August, when Solidarity has threatened a nationwide warning strike that could paralyze Polish industry.

So far, protests over the food shortages have been regional, culminating in today's strike in the industrial region of Silesia in southwestern Poland. Miners and steelworkers struck for four hours while transport was halted for two hours.

In its statement today, the government said it had "sufficient defensive means . . . to counteract the provocative acts of anarchy and actions that imperil the stability of the Polish state." Such vaguely worded warnings have been issued before, however, and there is no evidence that the authorities are seriously contemplating the use of force against strikers.

The new crisis again has raised the possibility of leadership changes, despite last month's personnel shake-up at the Congress. Premier Wojciech Jaruzelski, for example, has threatened to resign on at least two occasions unless given sufficient public support.

Should Jaruzelski either resign or be eased out over the coming weeks, the man who appears most likely to succeed him is Stefan Olszowski, the party's propaganda chief.

At the party congress, Olszowski is believed to have struck a deal with Kania under which he agreed to support the party secretary's reelection bid in return for favors later. He has also been building up a power base among emerging young politicians anxious to shake up the government bureaucracy.

Analysts cautioned, however, that alliances and bargains worked out at the congress could be upset by the pace of political developments in Poland.

On Solidarity's side, the most immediate problem is whether the leadership will be able to contain the bitterness felt by ordinary workers. Despite the government's allegations, it appears that in the last few days Solidarity leaders have not been instigating strikes, but rather have been finding themselves forced to endorse rank-and-file protests.