Pakistan angrily rejected its suspension from the Commonwealth on Friday, but leaders of the group of mainly former British colonies said the sanction was justified and would stand until democracy was restored.
A special ministerial group set up to safeguard democratic standards harshly criticised President Pervez Musharraf for his three-week-old state of emergency and suspended Pakistan's membership late on Thursday.
Pakistan is not attending the Commonwealth's Kampala summit but Foreign Ministry spokesman Mohammad Sadiq told Reuters in Islamabad the decision "is unreasonable and unjustified. Pakistan will review its association and further cooperation with the organisation."
Commonwealth Secretary-General Don McKinnon told a news conference: "Every country that has been suspended will say we didn't understand the circumstances prevailing in the country at the time ... We think we did."
"This wasn't a desire to heap retribution on Pakistan, this was a determination to live up to our principles."
This view was echoed by Prime Minister Gordon Brown, who said Pakistan was discussed by Commonwealth leaders when they began the three-day summit on Friday.
"Pakistan has obligations to meet. Pakistan has got to end the state of emergency ... Pakistan is suspended until the point at which free and fair elections take place and all of the conditions are met," he told reporters.
While Commonwealth suspension has few immediate practical effects, analysts say it could further isolate Musharraf, a key U.S. ally in the war against Islamic militancy, discourage foreign investment and undermine him domestically, where he is trying to fend off major opposition challenges.