ALKHAN-KALA, RUSSIA, JANUARY 28: Chechen snipers in high-rise buildings and trenches fired fiercely at Russian troops trying to advance on the centre of Grozny while a rain of Russian bombs and rockets blanketed the capital in thick smoke.International pressure was building on Russia to end the war, with UN Secretary-General Kofi Annan saying in Moscow that he wants the conflict to end as soon as possible. The Council of Europe's parliamentary assembly called for Russia to open cease-fire talks and to halt attacks on civilians, but rejected proposals to suspend Russia.Russian officials vowed that neither the military's aims nor its tactics would change."A concrete combat task has been set for the troops and they will fulfill it, regardless of how certain countries outside Russia feel about it," Presidential aide Sergei Yastrzhembsky told a news conference.The Russians have been struggling to seize Grozny for a month, and have concentrated for the past week on Minutka Square. Taking the Square would give federal forces leverage for pushing rebels out of the centre.Russian troops had advanced to within 250 metres of the square and were moving in on the city centre from the North and West, the Itar-Tass news agency quoted Lt Gen Gennady Trosehv, a top commander in the region, as saying.Earlier in the week, Russian troops had been about 400 metres from the Square. Troshev's claim could not be independently verified.Russian defense minister Igor Sergeyev claimed that the operation to take Grozny "is approaching a breakthrough," the Interfax news agency reported. "notwithstanding the losses among the storming groups in Grozny, the fighters' losses are far higher than ours."However, a Chechen leader claimed the Russians were being forced to retreat."Russian forces in many areas (of Grozny) have in fact been thrown back to the starting positions from which they started storming (the centre) in mid-January," rebel commander Aslanbe Ismailov said, according to Interfax.Many positions in the city have changed hands several times. The highly mobile rebels have moved around frequently and attacked the Russians from all sides. Russian servicemen have often taken buildings by day only to abandon them at night for fear of militant attacks.