The West has warned Russia of new sanctions after fighting flared up in eastern Ukraine despite a truce between the government and pro-Russian rebels.German Chancellor Angela Merkel said in Berlin that new sanctions could be applied if efforts to stabilise the situation were not speeded up.UK Foreign Secretary William Hague said inaction by Russia would mean a stronger case for sanctions.President Petro Poroshenko warned he might end the truce due to violations.The ceasefire began on Friday. On Tuesday, a Ukrainian military helicopter was shot down with the loss of nine lives.There was fighting overnight into Wednesday near the Russian border in Luhansk region.The Ukrainian military accused the rebels on Wednesday of breaking the ceasefire 44 times since it began. A separatist leader said there had "been no ceasefire".The truce is part of Ukraine's plan to end two months of fighting between government troops and pro-Russian insurgents who control key buildings in towns and cities across the east. More than 420 people have been killed in the region since mid-April, the UN estimates.President Poroshenko is expected to unveil proposals for constitutional reform to give regions greater self-government when he attends parliament on Thursday.On Friday, he is due to sign the long-delayed association agreement with the EU - a pact that was rejected in January by then President Viktor Yanukovych under heavy pressure from Russia.'Sanctions can return'Mrs Merkel welcomed the surprise decision by Russian President Vladimir Putin to cancel a parliamentary resolution authorising him to use Russian forces in Ukraine.The cancellation was ratified by Russia's upper house of parliament on Wednesday.While Mrs Merkel said the decision was "psychologically important", she told German parliament that Ukrainian soldiers continued to die.lineAnalysis: David Stern, BBC News, KievOne would suspect that the Ukrainian government's truce in the east is now a dead letter. Public outrage alone would seem to demand some sort of military retaliation.And if the Ukrainian government uses force, then very likely the Ukrainian insurgents and their Russian comrades-in-arms will answer in kind. An escalation seems inevitable.At this point, it is close to impossible to determine why the militants decided to carry out such a provocative act, just one day after they declared a ceasefire. Maybe this was some rogue element. Maybe the insurgents were never serious. Maybe Moscow told them to do it.Whatever the reason, the hopes of just 24 hours ago, that Ukraine's east could finally see peace, if only temporarily, ring especially hollow.line"Progress is slow... Diplomatic solutions are always preferable but if nothing else works, sanctions can be put back on the agenda," she said.Her Foreign Minister, Frank-Walter Steinmeier, said in Brussels that the helicopter attack showed "just how fragile the situation is and how fast progress made can be destroyed... by the separatists on the ground".UK Foreign Secretary William Hague, who was also in Brussels for a meeting of Nato ministers, said the downing of the helicopter was hard to reconcile with Mr Putin's avowed support for peace in Ukraine.Nato accused Russia of failing to respect "international commitments".In a statement, Nato chief Anders Fogh Rasmussen said Moscow was "using a new different type of warfare against Ukraine" and he promised a "package of long-term support measures for Ukraine, including the creation of new trust funds".Russia denies claims by Ukraine and the West that it is encouraging and arming the separatists.New fightingThe separatist commander in the rebel stronghold of Sloviansk, Donetsk region, announced on Wednesday that his forces had shot down the helicopter.In a statement, Igor Strelkov accused government forces of bombarding local villages into the night with artillery and mortars.A dawn mortar attack by the rebels on Wednesday inflicted "significant losses" on government forces near Sloviansk, he said. There was no independent confirmation of the claim.In Luhansk region, artillery and small arms fire could be heard early on Wednesday near the village of Biryukovo, 2km (1.2 miles) from the Russian border, eyewitnesses told Russia's Interfax news agency.Ukrainian MP Oleh Lyashko was quoted by Ukrainian media as saying border guards had come under attack by rebels at Biryukovo during the night. There were no casualties, he added, without giving his source.Insurgents had agreed on Monday to observe a ceasefire, proposed by the Ukrainian government, until Friday.But Alexander Borodai, prime minister of the self-styled Donetsk People's Republic, has said there is effectively no ceasefire because of government attacks.(BBC)Bakudaily.az