Myanmar has told the military to halt all offensives in ethnic minority conflict zones, a top official said Tuesday, as the regime pursues peace deals with guerrillas as part of wider reforms. The army-backed government, which last year replaced the long-ruling junta, on Thursday signed a ceasefire with Karen rebels in the eastern border region, raising hopes of an end to one of the world's oldest civil conflicts. A day later, President Thein Sein ordered the military not to attack any ethnic minority groups except in self-defence, Khin Yi, the minister of immigration and population, told AFP in an interview in the capital Naypyidaw. "The order covers the whole country," added the former national police chief, who was present at the signing of the ceasefire with the Karen National Union. But Khin Yi admitted that the order was sometimes proving hard to implement on the ground. "Some of the grassroot level units, when on patrolling duty, unexpectedly met each other and exchanged fire. Sometimes, the order (not to attack) did not reach to the grassroot level," he said. An earlier presidential order issued in mid-December for the military to cease attacks against ethnic Kachin guerillas in the north of the country failed to stop heavy fighting in the region, according to the rebels. The Kachin guerrillas have not yet taken up the government's offer of peace talks, Khin Yi said, but added that the authorities aimed to organise a meeting of all the ethnic groups if ceasefires are agreed. In December, a ceasefire deal was reached between the local government and the Shan State Army-South, another major ethnic militia. Civil war has gripped parts of Myanmar since independence in 1948. An end to the conflicts and alleged rights abuses involving government troops is a key demand of Western nations which impose sanctions on the regime. Vast numbers of villagers in Karen state, scene of Myanmar's oldest insurgency, have been forced to flee, and tens of thousands of these refugees live in camps across the border in Thailand. Rights groups say the government's counter-insurgency campaigns over the years have deliberately targeted civilians, driving them from their homes, destroying villages and forcing them to work for the army. Fighting in northern Kachin state between the army and rebels since June last year has displaced tens of thousands of people. Myanmar's previous junta justified decades of military rule as a way of maintaining stability and unity in a country where one-third of the population is made up of ethnic minorities. The country now has a nominally civilian government following a controversial November 2010 election, but its ranks are filled with former generals including Thein Sein, who was premier under the junta. The regime has surprised observers with a series of reforms, including talks with democracy icon Aung San Suu Kyi, who has been allowed to stand in an April by-election, and the release of hundreds of political prisoners. Suu Kyi said on Sunday that an end to the ethnic conflicts was a priority. "I think it's a matter of both sides being more flexible," she told reporters, calling on the predominant Burman ethnic group "to be more broad-minded and to be more generous".