Davos, Switzerland (CNN) -- Pakistan's former leader Pervez Musharraf will "certainly" be arrested if he returns to Pakistan, Prime Minister Yousuf Raza Gilani said Friday.
"In fact there had been murder charges against him, and there had even been some very grave charges against him, and the Supreme Court had already given a verdict against him," Gilani told CNN from the Global Economic Forum in Davos.
"Certainly when he'll come back, he has to face those charges and certainly be arrested," he said.
Musharraf announced plans to return from exile in late January and to run in upcoming elections, but his party said he was reassessing those plans when Pakistan's elected government warned that if he returned, he faced arrest.
Pakistan's upper house of Parliament passed a non-binding resolution earlier this week demanding Musharraf be arrested and tried for treason for unconstitutional acts during his regime, Sen. Muhammad Ibrahim Khan said.
The charges against Musharraf are in connection with the 2007 assassination of former Prime Minister Benazir Bhutto.
A U.N. report in 2010 accused Musharraf's government of failing to protect Bhutto, who had returned to Pakistan from her own exile to run for office.
Musharraf, who has been living in London and Dubai since resigning in 2008, has denied the allegations, arguing that Bhutto had police protection and took unnecessary risks, but a Pakistani court still issued a warrant for his arrest.
Separately, Gilani admitted "a lot of challenges" in the war on terrorism, including militancy in the country's northwest region.
"We are fighting for our own selves, for our own survival, because these militants, they have killed 30,000 innocent people, 5,000 brave soldiers," he said.
The fight against terrorism has caused a "loss of economy," Gilani said, but investment in the country remains.
"Yes, we are fighting a war on extremism and terrorism, and we're a front-line state, yes, there are a lot of challenges," he said. "But it doesn't mean that there is no investment coming to Pakistan. We have offered very lucrative incentives for the investment in Pakistan and there are a lot of investment coming to Pakistan."
Gilani also said people in Pakistan are "bitter" over an attack by NATO forces last November that killed two dozen Pakistani soldiers near the Afghan border. NATO has said the attack was "unintended."
"We have paid so much price for the war on terrorism," Gilani said. "People should appreciate our struggle."