Zimbabwe's Robert Mugabe warned today he would not step down even if he does lose the presidential election to be held later this month. "We shed a lot of blood for this country. We are not going to give up our country for a mere 'X' on a ballot. How can a ball point pen fight with a gun?" He said in the government mouthpiece Herald newspaper. Mugabe said that the nation threw off colonial domination in a guerrilla war in 1980 - and his party was ready to fight again to stop the pro-Western Movement for Democratic Change party from gaining control of the government. Meanwhile, British Prime Minister Gordon Brown, speaking in London with President George Bush, warned that international election monitors must be allowed to monitor the runoff or risk having Mugabe's "criminal regime" steal the election. "(Mugabe's) criminal cabal ... threatens to make a mockery of free and fair elections in Zimbabwe," Mr Brown said. Mr Bush said the US would work with Britain and others to make sure the runoff poll is conducted to international standards. ``The people of Zimbabwe have suffered under the Mugabe leadership and we will work you to ensure this process leads to free and fair elections, which obviously Mr Mugabe does not want to happen,'' Mr Bush said. Concerns have mounted over the run-off election in less than two weeks between opposition leader Morgan Tsvangirai and Mugabe. Since the first round of voting on March 29, opposition supporters have been attacked and arrested, and Mr Tsvangirai's attempts to campaign have been thwarted by police. He has been detained at least six times and two campaign buses have been impounded.