* Fiery cleric's party may contest elections
* A threat of more protests if demands not met (Adds Karachi violence)
By Mubaher Bukhari
ISLAMABAD, Jan 18 (Reuters) - A cleric who has been pushing for electoral reforms in Pakistan will resort to street protests aqain if the government does not abide by an agreement that eased a political crisis, an aide said on Friday.
Muhammad Tahirul Qadri, who has a history of ties with the military, reached a deal with Pakistan's ruling coalition on Thursday that will give his party some say over the formation of a caretaker government ahead of elections this spring. Qadri's party may also participate in the elections.
The cleric's reappearance on Pakistan's political stage a few weeks ago after years of living in Canada, and his calls for the military to play a role in forming an interim administration, has raised speculation he may be backed by the country's powerful army.
Qadri and the military deny this.
The cleric, who led four days of street protests in the heart of the capital aimed at forcing the government to resign, will keep pushing for political reforms and a halt to corruption, said his spokesman.
"We will ensure implementation of the agreement with full letter and spirit," Qazir Faizul Islam, secretary of information for Qadri's charity, told Reuters.
"If the government tries to deviate, we will force them to follow through the power of the people and media."
Aside from giving Qadri a voice in who leads the caretaker administration, the government also agreed to dissolve parliament before a scheduled date of March 16, although it did not specify a date.
It also said elections would be held within 90 days of the dissolution and electoral reforms would continue to be discussed.
An announcement of an election date could come during a parliament session on Monday.
"After signing the agreement for electoral reforms, we are part of the electoral process. We might take part in elections," said Islam, adding however that Qadri had no ambitions to become prime minister.
But the focus for the moment seems to be on the interim administration that will be formed after the dissolution of parliament and will oversee the elections.
A new political crisis could erupt if Qadri tries to promote candidates for caretaker prime minister seen to be sympathetic to the military, which has ruled the country for more than half of its history as an independent nation.
Qadri supported a 1999 military coup, and praised the military during speeches this week, appealing to thousands of supporters and members of the middle and lower class who have grown tired of Pakistan's dynastic politics.
Any disagreements between Qadri and the government on electoral reforms could also bring fresh turmoil, distracting the state from a host of challenges, ranging from a Taliban insurgency to crippling power cuts to a fragile economy.
Sectarian violence has risen sharply.
Many busineses shut down on Friday in Pakistan's commercial capital and biggest city Karachi after the killing of a politician in a drive-by shooting, police said, which raised fears of a fresh wave of sectarian violence.
"Chances are low that the government will demonstrate progress on other Qadri demands (like reforms) before elections are held, increasing the likelihood that this timetable will fail and a caretaker government could stay on indefinitely," said Shamila Chaudhry, South Asia specialist at the Eurasia Group.
Qadri's call for a campaign to root out corruption could also create obstacles and delays.
"Corruption is rampant among all political actors, not just the current government," said Chaudhry.
"So true implementation of the declaration will require a complete overhaul of political behaviour in Pakistan - a virtually impossible task before elections if they are to occur by June."
The government got some relief on Thursday when the chief of the state's anti-corruption agency rejected a Supreme Court order to arrest Prime Minister Raja Pervez Ashraf.
Ashraf is alleged to have been involved in kickbacks in transactions involving power plant rentals when he was power minister - allegations that he denies.
The case was adjourned until Jan. 23, judges said.
One of the investigators of the allegations against Ashraf, Kamran Faisal, was found dead in his apartment, police said on Friday. It was not clear if it was a suicide or murder, said a police official. He was found hanging from a ceiling fan. (Writing by Michael Georgy; Editing by Raju Gopalakrishnan and Ron Popeski)