Turkish soldiers hunting Kurdish rebels have entered Iraqi territory on a broad front in an offensive against guerrillas who have been attacking military installations and troops in the southeastern part of Turkey since mid-August.

The military operation, codenamed "Sun," is the second Turkish incursion into Iraq in a year and a half. It began after a weekend meeting in Baghdad between Turkish Foreign Minister Vahit Halefoglu and Iraqi President Saddam Hussein. Authorities here stressed that the operation is not a hostile act against Iraq and has the full approval of the Baghdad government. Turkey launched a similar operation into Iraq in May 1983 with Iraq agreeing to the unprecedented waiver of its northern frontier's inviolability.

Authorities here released few details about the current operation. Military sources did disclose that Turkish troops were operating along a 75-mile front that was about 18 miles deep and were reported by Reuter to have penetrated up to 10 miles into Iraqi territory.

It was unclear, however, how many Turkish troops were involved in the fighting and precisely when they crossed into Iraq. Military sources said they believed that there are more Kurdish rebels in the battle area than before and that they are better organized. As a result, the sources said they expected the military operation would take longer than the reported three-day thrust into Iraq last year.

According to Agence France- Presse, Turkish Prime Minister Turgut Ozal, speaking to parliament, accused rebels of the Kurdistan Democratic Party of Massoud Barzani of carrying out the attacks in southeastern Turkey that prompted the operation. He said the guerrillas had been trained in Palestinian camps in Lebanon and Syria and were receiving directions from "foreign powers who do not want to see Turkey strengthened."

Ozal told members of parliament that the Persian Gulf war had hindered the capability of Iran and Iraq to halt Kurdish guerrilla activity against Turkey launched from their soil. Agreement had been reached with Iraq for "joint efforts to combat terrorism," Ozal said, adding that "similar cooperation was being sought with Iran."

In Tehran, a spokesman for Barzani, whose party opposes Saddam Hussein, said he had gone to northern Iraq and would lead his men in opposing the Turkish Army operation.

Reuter, quoting Turkish newspapers, reported that up to 40 guerrillas already had been captured and that one noncommissioned Turkish officer from a commando squad had been killed when his helicopter crashed because of a technical problem.

Kurds, who inhabit an area of rugged mountains extending from southeastern Turkey through northeastern Iraq to northwestern Iran, have long wanted an independent state. Although they make up one-fifth of the population in Turkey, they have no official standing there as Kurds, and their language is not recognized. Turkish officials routinely describe Kurdish separatists as "terrorists."

Sources in Ankara claimed that there are more than 17,000 Kurdish guerrillas in the area of the current military operation. The incidents that sparked the incursion began on Aug. 14, when guerrillas attacked a Turkish border town called Sirvan in an apparent effort to divert the attention of local security forces.

This was followed by two well-coordinated attacks the next evening on Eruh and Semdinli. Those towns are more than 200 miles apart and are separated by rugged mountain terrain. Yet both attacks were launched at precisely the same time and followed the same pattern: about 40 rebels entered each town and took control for about an hour. According to eyewitnesses, they were well-organized and brought medical teams with them.

Turkish soldiers immediately began a counterthrust inside Turkey but were unable to stop the attacks. During the past two weeks, 16 Turkish troops have been killed in ambushes in the area. Turkish officials said today that this continuing insurgent activity had prompted the new incursion, which is aimed at Kurdish staging bases inside Iraq.

But observers here believe that it may be difficult for the Turkish military to put an end to the attacks if rebels escape this time into northern Syria. According to diplomatic sources here, Syria recently has begun to permit Kurdish groups to meet and plan strategy in Damascus.