Bhutto, whose PPP is currently the largest opposition party in Pakistan, plans to contest parliamentary elections due by mid-January.
Faced with street protests and growing political isolation, Musharraf has been negotiating a power-sharing deal with Bhutto.
The PPP is seen as not being in a position to block Musharraf's re-election, but it could damage the credibility of the election process if it boycotted the vote.
Bhutto has also disputed government claims that corruption cases against her has been dropped.
"This is just a typical disinformation campaign by the present regime," she told reporters in London.
Bhutto said Musharraf's continued rule in uniform was fuelling extremism in Pakistan.
"The longer the military regime continues in this fashion, the more anarchic the situation becomes," she said.
"I am afraid we are heading for a situation which could lead to street agitation."
Pakistani authorities opened Islamabad's Red Mosque on Wednesday, nearly three months after more than 100 people were killed when commandos stormed the compound to end a siege by radical students.
Hundreds of people turned up to offer prayers at the newly painted and repaired Lal Masjid, or Red Mosque, which was reopened on the orders of the supreme court.
An earlier attempt to reopen it sparked violent clashes between religious factions and police and a suicide bomber killed 13 people near the mosque on the same day.
But there was no trouble on Wednesday as police removed barbed wire and security posts from around the mosque.
The mosque's bullet-riddled walls and blasted outer walls have been repaired. The authorities had torn down the religious school after the siege.