LONDON — London Mayor Sadiq Khan on Tuesday launched his re-election campaign, attacking Prime Minister Boris Johnson for failing to tackle a crisis in affordable housing in the British capital. Conservative party leader Johnson was mayor before Khan, running local services for London"s nearly nine million people between 2008 to 2016. But Khan, from the main opposition Labour party, said his predecessor failed to tackle rough sleeping and a shortage of lower-cost housing. He accused the prime minister of repeatedly blocking his attempts to introduce rent controls, which he argued would help ease the problem. "When I arrived at City Hall we inherited a terrible mess, the pipeline was empty because Boris Johnson only cared about building luxury flats for overseas investors," Khan said. Rough sleeping had doubled during Johnson"s time in charge, he claimed. The May 7 vote, at which Khan wants to secure a second four-year term, would be a "referendum on rent controls", he said, vowing to secure the powers to do so from central government. Khan wants to set up a private rent commission in the capital and introduce measures to keep costs down, citing New York and Berlin as examples. The London Renters Union, which represents thousands of private renters, said the plan could transform the housing system and stop sky-high rents. But it pointed out: "Rents need to be linked to incomes and simply settling for caps on rent rises won"t ease the real suffering London"s renters face." Independent mayoral candidate Rory Stewart, a former Conservative minister, accused Khan of four years of inaction. "Instead of doing his job, with the powers he has, to build affordable houses, the mayor has concocted a hollow fight with government to simply freeze rents at unaffordable levels," he tweeted. Property and rental prices are higher in London and southeast England than elsewhere in Britain because of higher demand and population density. According to a BBC briefing on housing last month, one in 53 people were homeless in London — the highest in the country. In Newham, in east London, the figure rises to one in 24. The number of rough sleepers in England and Wales has more than doubled since 2010, government statistics suggested, with 8,655 people on the streets in London in 2018. A lack of social housing has led to long waiting lists for local authority homes. In Newham, for example, more than 25,000 households were waiting for fewer than 600 properties. — AFP