A suicide bomber crashed a truck packed with explosives into a police building in Russia's volatile Ingushetia province Monday, triggering a blast that killed at least 20 people and injured scores of others, authorities said. The attack was the deadliest in recent months in the North Caucasus, where the Kremlin has been put on the defensive by separatist violence and its security forces have been accused of employing harsh tactics against civilians. More than 20 people were killed in clashes in the largely Muslim region Thursday and Friday, following the murders of two human rights workers in Chechnya and the assassination of the Ingush construction minister earlier in the week. The truck plowed through the gates of the police headquarters in Nazran, the largest city in Ingushetia, located east of Chechnya, as police officers were arriving for morning roll call, officials said. The explosion occurred in a heavily populated area, damaging several nearby buildings and causing a fire that burned for hours. Ingushetia's Kremlin-appointed president, Yunus-Bek Yevkurov, who was badly wounded in another suicide bombing in June, issued a statement blaming the attack on Islamist militants seeking revenge for recent security operations along the region's border with Chechnya that left more than 30 dead. 'It was an attempt to destabilize the situation and sow panic,' said Yevkurov, a former military intelligence official installed by President Dmitry Medvedev in October. In a radio interview scheduled to be broadcast Monday night, Yevkurov also accused the United States and its allies of backing the militants to weaken Russia. 'I am far from believing that the Arabs are behind all of this. There are other, more serious forces,' he said in excerpts broadcast by Russian News Service radio. 'The West will strive to prevent Russia from restoring its former Soviet-era might. ... We understand who is interested: the United States, and the United Kingdom, as well as Israel. It's quite possible.' Human rights groups say Russian security forces have fueled the insurgency in Ingushetia by waging a campaign of abductions, torture and extrajudicial killings. After a top opposition figure there was shot to death while in police custody last fall, Medvedev dismissed the provincial governor, an ally of Prime Minister Vladimir Putin, and replaced him with Yevkurov, who had reached out to the opposition as well as the militants in an attempt to ease tensions. 