DUBAI, Feb 3 (Reuter) - An Iraqi militant group linked to al Qaeda vowed on Saturday to widen its attacks to all parts of Iraq instead of just focusing on Baghdad, after Washington announced plans to beef up its forces in the capital. The leader of the self-styled Islamic State in Iraq, a body set up by al Qaeda's Iraq wing and other Sunni militant groups in October, said in a Web recording the campaign would stop only "when (U.S. President George W.) Bush signs a surrender accord". "We today announce a strategy ... which is wider and wiser with God's power. It does not involve Baghdad alone but all parts of the Islamic state," said the speaker, identified as Abu Omar al-Baghdadi, leader of the group. In January Bush said he would send 21,500 additional U.S. soldiers to Iraq in an effort to crack down on sectarian killings and insurgent attacks, especially in Baghdad. Baghdadi said Bush was giving Muslim fighters a chance "to slaughter the wounded crusader giant and take advantage of the collapsing morale of its soldiers and commanders". The authenticity of the tape could not be verified, but it was posted on Web sites used by al Qaeda and other insurgent groups in Iraq. Baghdadi called on other Sunni Muslim militant groups to join his "state" to unify insurgent ranks.