In one section of the guide, titled "Some do's and don'ts", people being deported from the UK are advised to: "Try to be 'Jamaican' -- use local accents and dialect (overseas accents can attract unwanted attention)."
Another section on "Local tips" reads: "'Deportation is not a sentence or punishment but a second chance to build a new life and make a meaningful contribution to build the nation.' (as stated by a deported person)."
Labour lawmaker David Lammy, who slammed the government's handling of legal Caribbean immigrants in a speech Monday, took aim at British Prime Minister Theresa May and Home Secretary Amber Rudd after reading the guide.
"How exactly can someone pretend to 'be Jamaican' when they are British and have lived here all their lives? What is going on @AmberRuddHR @theresa_may @ukhomeoffice?" Lammy tweeted on Tuesday.
"This document harks back to 'repatriation' campaigns. This document was published when Theresa May was Home [Secretary], promoting her hostile environments policy -- the starting point for the injustices that we are seeing writ large for the Windrush generation."
"Hard to believe this document was written and published. The fact that the [government] feels this is an appropriate way to treat the ancestors of those Caribbean pioneers who were invited to Britain as citizens tells its own sad story about the treatment of immigrants in our country," he added.
Responding to the criticism, the Home Office said the document offers advice to people who are in the UK illegally, not the Windrush generation.
"This document has nothing to do with people from the Windrush generation, who are in the UK legally. As the Home Secretary has made clear today, the Home Office has set up a dedicated team to help people from that group to get the right paperwork to confirm their status in the UK," a Home Office spokesperson told CNN.
The Home Office also said that the lines which advise people to "try to be Jamaican" in the "do's and don'ts" were specifically written by a Jamaican non-governmental organization.
The flap over the guide comes amid an uproar over the government's treatment of some Caribbean immigrants and their children, who were invited by Britain in the late 1940s (some aboard the Empire Windrush passenger line) but are now struggling to prove their British citizenship.
Regulations introduced by Theresa May when she was Home Secretary require employers, landlords and health service providers to demand evidence of legal immigration status. In 2012, May described the measures as designed to create a "hostile environment" for people who were in the UK illegally.
The trouble is, many of the Windrush children don't have the required documentation. As a consequence, some lost their jobs, others were evicted from their homes, and a few were reported to have been threatened with deportation.
The bubbling controversy exploded into a full-blown scandal at the weekend. For the first time in 20 years, the UK is hosting the Commonwealth Heads of Government Meeting, a biennial summit of leaders of Commonwealth nations. A delegation of Commonwealth leaders requested a meeting with the Prime Minister to discuss the Windrush issue, which Downing Street -- to widespread consternation -- declined.
Stung by a wave of negative publicity, the government backed down and announced May would meet the leaders on Tuesday.
During the meeting, May apologized for the "anxiety" felt by legal migrants to Britain who have been denied services or feared deportation.
"I take this issue very seriously," May said Tuesday. "I apologize to you today because we are genuinely sorry for any anxiety that has been caused."
May's apology came after Home Secretary Amber Rudd was forced to appear before MPs in the House of Commons on Monday. Rudd apologized for the "appalling" treatment of some of the Windrush migrants and promised that none of them would be deported for lack of documentation.
CNN's Stephanie Halasz and Hilary Clarke contributed to this report.