ISLAMABAD, PAKISTAN, JAN. 26 -- U.N. special negotiator Diego Cordovez returned to Pakistan this afternoon after talks in Afghanistan, declaring that "a lot of differences" remain between the two countries on a negotiated settlement of the eight-year-old war there.

The U.N. undersecretary general, who usually adopts an optimistic tone on the long-running indirect talks, told Pakistan television that this round of shuttle diplomacy did not appear to have brought a peace agreement any nearer.

"There are a lot of differences and we will have to work them out," Cordovez said. Asked if he was any closer to a settlement, he responded abruptly, "I don't think so."

Cordovez, who had meetings with Afghan leader Najibullah and Foreign Minister Abdul Wakil in Kabul, immediately went into talks with Pakistani Foreign Ministry officials. He also briefed the U.S. and Soviet ambassadors.

The Ecuadoran diplomat began his current round a week ago in Islamabad. On arrival in Kabul over the weekend, after initial talks with Pakistani officials, he was quoted as having said that both sides appear "very determined" to reach a political settlement quickly.

It is unclear what has led to the note of caution registered today, but Pakistani officials have been warning that a number of key issues have to be resolved before formal talks can be called in Geneva.

Cordovez has been aiming at a new Geneva session by the end of February and has echoed statements by Soviet leaders that it "could be the last," leading to the withdrawal of the estimated 120,000 Soviet troops in Afghanistan.

Pakistani President Mohammed Zia ul-Haq underscored in an interview last week that his government would not sign an accord with Najibullah's government, saying it draws its power only from the presence of Soviet troops. This implies that an agreement to end the conflict would be signed only with a successor government to Najibullah's, a point emphasized by other Pakistani officials this week.

Cordovez presumably carried this message to Kabul. It is unclear how the Afghans responded, but Cordovez's cautious remarks could indicate a wide gap between the two sides.

The U.N. negotiator is expected to continue his talks with Pakistani Foreign Ministry officials Wednesday and his aides left open the possibility of continuing his shuttle.

As diplomatic efforts continued, Soviet and Afghan government troops appeared to have pulled back from their efforts to keep open the road to the garrison at Khost in eastern Afghanistan.

The road was opened in heavy fighting early in January to resupply a besieged garrison. But Kabul Radio and the official Tass Soviet news agency announced over the last two days that the Afghan Army had "withdrawn following requests from Afghan tribal leaders."

Guerrilla commanders in the area today claimed that resistance units had driven the Afghan Army and Soviet troops from the narrow mountain roadway, but there were reliable reports in Pakistan that Kabul may have been able to strike a deal with leaders of the Zadrani tribe -- through whose territory the road passes -- promising a withdrawal in return for limiting of attacks or an end to them.

The Afghan Army has built a number of outposts along the road, according to reliable reports, and it is unclear whether these will continue to be manned. Now that the Khost garrison has been resupplied, analysts suggested that the Soviets may have concluded that it was no longer necessary to try to man the vulnerable roadway under intense winter conditions.

The statements announcing that the troops would be pulled off the roadway also threatened retaliation if resistance forces tried to close it again.