An expansion of Adelaide Oval number two, which sits west of the main oval, will go ahead after the Adelaide City Council approved the removal of significant trees in the area.

Lord Mayor Martin Haese told 891 ABC Adelaide 15 trees will need to be removed to allow for the expansion.

He said although a small number of the trees were classed as significant, the council voted last night to support the development plan.

"It brings Adelaide Oval number two, the playing field, up to international standards, so of course there was a long deliberation," he said.

"But council decided that on balance of probability and given we'll be planting more trees as a result of the ones we're losing that we would proceed with it."

Adelaide Oval number two will be expanded in the north-west corner, alongside Montefiore Road.

Mr Haese said the expansion was part of the wider Adelaide Oval master plan.

"It's an extra 1,000 square metres of playing field area in that north-west tip of the Adelaide oval number two area, so it's not an expansion of the entirety of the oval itself, it's just one part of it," Mr Haese said.

"As people know there's been a great deal of work right around the circumference of Adelaide Oval in terms of landscaping so this really does complete that picture."

Mr Haese said it was not practical to relocate the significant trees, but other trees would be planted to complete the landscaping.

"[The expansion] will also provide for a running track which will go around the circumference of part of the oval, which evidently was part of the master plan itself, the 15 trees will be removed and the equivalent if not greater number of trees will be planted in their place and this work will commence early next year."