By Sarah Rainsford
BBC News, Moscow
Russian security forces working in Chechnya have seized a truck loaded with explosives.
They say the vehicle was destined for use in a major terrorist attack.
The Kamaz truck was seized on Thursday morning, close to the Chechen capital, Grozny, a Russian military spokesman has confirmed.
The announcement comes as much of Russia is on high alert for possible security threats ahead of next week's celebration of the end of World War II.
More than 50 heads of state and other dignitaries are expected to attend.
Last year, a bomb exploded killing the pro-Moscow president of Chechnya, Akhmad Kadyrov, as he attended a Victory Day parade in Grozny.
Security forces had stopped the vehicle, suspecting it was fitted with false license plates.
On board, they discovered more than a tonne of explosives.
The military spokesman told the BBC the truck was primed for detonation by remote control.
He suggested only Chechnya's chief warlords could possibly be linked to planning such a serious attack, though he admitted as yet there was no hard evidence.
The truck driver and a passenger are now being questioned.
Earlier in the day, Russian security forces also claimed to have averted a series of planned terror attacks, using a cyanide-based substance.
They say the targets were major cities in the North Caucasus.