By Aung Hla Tun YANGON, Sept 26 (Reuters) - Myanmar's junta put armed police and barbed wire barricades on the streets of its main city on Friday, the first anniversary of a bloody military crackdown on major anti-government protests. Security was especially tight near the house of detained opposition leader and Nobel laureate Aung San Suu Kyi, and in front of City Hall, where a small bomb exploded on Thursday, wounding seven people. Official papers said none of the victims were seriously hurt, and urged public vigilance against the "bombers and terrorists in disguise". No group was blamed for the blast. Normally in the aftermath of such incidents, the junta immediately points the finger at underground democracy activists or the ethnic guerrilla groups that have fought against the Burmese majority almost since independence from Britain in 1948. "The authorities concerned are conducting investigation into the case to expose the saboteurs and explosives," said the New Light of Myanmar, the junta's primary mouthpiece. The paper also said bomb squad officers found and defused a second device left near the site of the first explosion and timed to detonate an hour afterwards. Even though it is impossible to say who might have been behind the bombs -- one diplomat suggested it could even be the military trying to justify its heavy security presence in Yangon -- the timing was significant. Exactly a year ago, the junta ordered troops into central Yangon to end a week of massive demonstrations led by Buddhist monks calling for the removal of 45 years of army rule. At least 31 people were killed when soldiers opened fire on crowds across the former capital, the United Nations estimates. Western governments say the real toll is probably higher. A Japanese journalist was among those shot dead. A further 3,000 people were rounded up in a sweep of dissidents and democracy activists that is still under way and makes any repeat of the 2007 demonstrations extremely unlikely. Earlier this month, female activist Nilar Thein, a student leader in a brutally crushed democracy uprising in 1988 and an organiser of last year's protests, was detained after a year on the run. She went into hiding, abandoning her four-month-old daughter, when her husband was arrested in August for helping stage the small fuel and food price demonstrations that snowballed into the monk-led marches a month later. The junta says all but a handful of those detained have been freed, although rights groups say 700 are still behind bars. Myanmar's longest-serving political prisoner, 79-year-old journalist Win Tin, was freed this week after 19 years in prison. However, another senior member of the opposition National League for Democracy (NLD) was rearrested only 24 hours after being released from a prison in Katha, 1,000 km (650 miles) north of Yangon, NLD spokesman Nyan Win said. (Writing by Ed Cropley; Editing by Jerry Norton)
