Pakistan President Asif Ali Zardari has said the best way to pay tribute to slain former prime minister Benazir Bhutto on her fourth death anniversary is to foil anti-democracy "conspiracies".

"Today we pay tributes to her. The best way to do it is to defend and protect democracy and democratic institutions in the country and foil all conspiracies against it," The News quoted Zardari, as saying.

"Let us on this day re-dedicate ourselves to the democratic mission of Shaheed (martyr) Mohtarma Benazir Bhutto whose life was dedicated to fighting dictatorship and those seeking to defame and dismantle democratic institutions," he added.

His statement came amid escalating tensions between the army and government over the Memo Gate scandal.

Zardari slammed Bhutto's assassination as a conspiracy.

"Her assassination was a conspiracy to rid the world of its best weapon to combat international violent extremism. It was a conspiracy to rob Pakistan of its best hope to establish a fully functional democracy," he said.

Bhutto, twice-elected prime minister and wife of Zardari, was killed in a gun and suicide attack on December 27, 2007 in Rawalpindi, after addressing an election rally.