RUSSIA'S threats to relaunch the war in Chechnya unless rebels hand in their guns reflects Moscow's growing frustration that the six-week-old truce in the breakaway republic is not leading anywhere. Fierce outbursts this week from both the Russian and Chechen delegates - each blaming the other for cease-fire violations - have upset the uneasy limbo that has reined in Chechnya since the two sides reached a military accord on July 30. Under that agreement Moscow was to withdraw the bulk of its forces from Chechnya, and guerrillas loyal to rebel leader Gen. Dzhokhar Dudayev were to hand over their weapons. But most of the Russian soldiers that took part in the bloody seven-month war to crush Chechen aspirations to independence are still deployed in the region - although they are largely confined to barracks - and General Dudayev's men have turned in only 1,500 guns according to the Russian count, well below the 45,000 weapons that Moscow is expecting. An apparent assassination attempt yesterday against Moscow's special envoy to Chechnya, Oleg Lobov, seemed only to make a settlement more elusive. A parked car exploded as Mr. Lobov, who is also secretary in Russia's powerful Security Council, passed near the Chechen capital of Grozny. (Lobov was uninjured.) The day before, Russians had warned Aslan Maskhadov, the rebel commander in chief, that they would ''take unilateral steps to disarm illegal groups, using force'' unless all guns were turned in by the end of the month. But this demand seemed unlikely to be met. Chechens showed no sign of honoring a pledge made last week to hand in their heavy weapons, arguing that the Russian side had given no indication of when it would pull its troops out. Furthermore, Mr. Maskhadov said yesterday that the Chechens were returning their big guns to combat positions instead of turning them in. At the heart of the dispute is a fundamental uncertainty over who is actually in charge of Chechnya. After a long and arduous campaign that cost thousands of civilian lives, the Russian Army appeared to be in physical control of most of Chechnya by the end of July, and the Kremlin counted on a loyal Chechen leader, Salambek Khadjiyev, to establish political control of the republic's towns and villages. In practice, however, as Dudayev loyalists have filtered back to their homes, it is they who have set up armed ''self-defense units,'' permitted under the truce accord, and have thus effectively taken command in the villages. Russian troops hold positions outside all the settlements and sporadically patrol the ruined streets of Grozny. But they regularly come under fire at night; Tuesday's statement accused rebels of killing 26 Russian soldiers and wounding 153 in 408 incidents since Sept. 1. In the meantime, negotiators have met regularly at the headquarters of the Organization for Security and Cooperation in Europe in Grozny. But they have made no headway in their search for a longer-term political solution to the Chechnya crisis, being entirely taken up by their efforts to make even the military agreement stick. Moscow still insists that Chechnya is part of the Russian Federation; the Chechens are equally adamant that they will settle for nothing less than sovereign independence. Local elections due to be held on Nov. 5, after which political negotiations were planned, are now almost certain to be postponed, according to negotiators. Reconstruction efforts, to repair the damage done by heavy bombing and artillery raids during the war, are mostly stymied for lack of money. Lobov said recently that at the current pace of work it would take 20 years to rebuild Grozny alone. But his bid to extract more reconstruction funds from the Treasury has failed, and the government will now be forced to ask parliament to vote an extra five trillion rubles ($1.1 billion) to pay for the work.