The cost of re-organising Oxford's education system is set to cost £35m -- 16 per cent more than planned.

Work to prepare the city's first and secondary schools for the changeover from a three- to two-tier education system is on schedule.

But the cost to Oxfordshire County Council has risen by £5m on initial estimates due to rising building costs, additional unforeseen problems at some school building sites, and the addition of new facilities.

At Cheney School in Headington, the council decided to add a new sports hall and was forced to build a new electricity substation, while the cost of building work at SS Philip and James Primary School in Leckford Road rose when Japanese Knotweed -- a plant capable of destroying concrete foundations -- was discovered on the site.

The increased cost has been funded by borrowing cash from an insurance fund surplus and the council's balances. The changeover, which comes into effect in September 2003, will see first, middle and upper schools replaced by primary and secondary schools, and will be paid for by the sale of redundant school sites. The council's executive insists the change will be accomplished at no lasting expense to the council.

But the council's only Green member, Craig Simmons, said the use of council cash to supplement the schools reorganisation budget, was "scandalous".

He said the cash should instead have been used to fund social services, which are facing cutbacks of nearly £9m, including the closure of three respite centres for disabled children.