Chris Woodhead, the chief inspector of schools, has walked into political controversy by announcing a 12-month inspection blitz on two London boroughs just as the Conservative party conference gets under way.

Lambeth and Waltham Forest are to receive special attention from the Office for Standards in Education because they have a large number of failing schools.

The announcement follows the Prime Minister’s speech to grant-maintained heads in Birmingham last month, where he said that inspections would increasingly focus on “authorities or schools where standards are poor”.

The Office for Standards in Education has already announced an investigation of how reading is taught in three London boroughs with poor results: Islington, Tower Hamlets and Southwark.

The timing was immediately criticised by Labour’s education spokesman, David Blunkett, who said that the announcement had obvious political ramifications. “It would be normal to expect an announcement of this sort to be timed away from the high-profile conference season. It is beholden on OFSTED to avoid anything which would label them as a tool of Government,” he said.

Both Lambeth and Waltham Forest gave a cautious welcome to the promised extra attention from the inspectorate.

Lambeth - which has five schools deemed to be failing out of 17 inspected - and its new chief executive, Heather Rabbatts, are attempting to overcome a troubled history. Formerly a Labour borough, it has been racked with allegations of corruption, accompanied by multiple inquiries. There is no overall political control.

Lambeth, which is advertising for a new executive director of education, recently received a damning report on the Mostyn Gardens primary school, where inspectors said conditions were some of the worst they had seen.

Four Waltham Forest schools out of the 12 inspected were judged to be failing, including one which cannot yet be named, and a fifth has “serious weaknesses”. The borough is run by a Liberal Democrat-Labour coalition.

Mr Woodhead went out of his way to deny that the OFSTED initiative was politically motivated. “This is not in any way a political decision. In my judgment this was a much-needed, necessary move,” he said.

“It’s imperative that we make the announcement as soon as possible. We have to set the process in motion. This was a window of opportunity before the Tory party conference start date. We can’t hang about. If we’d made the announcement last week, we’d have been accused of making it during the Labour party conference.”

He acknowledged that many city children had deprived backgrounds. But, he said: “You can’t excuse or explain why schools fail in terms of the socio-economic nature of the catchment area.”

Mr Woodhead said that the failing schools displayed a lack of expectation for their pupils; that headteachers did not give rigorous leadership; and that the staff failed to use an appropriate range of teaching methods.

“Children in inner-city schools have the same right to a decent education as their more fortunate peers in leafy suburbs,” he said. “If they are not getting a decent education, we must know. We can’t as a country tolerate a situation where hundreds, perhaps thousands, of young people are receiving an inadequate education.”

He said that the additional inspections, which include grant-maintained schools, will be undertaken without affecting the four-year schedule for other schools.

Nationally, nearly 100 schools have been judged to be failing by OFSTED, and a further 10 per cent are said to have “serious weaknesses”.