ATHENS, Sept 30 (Reuters) - Greek private sector unions will stage a 24-hour strike on Wednesday to protest against changes to labour laws planned by the newly-elected conservative government.

Protesting workers and pensioners are expected to rally and march in central Athens around midday.

The planned reforms include moves to change some rules governing the calling of strikes, allowing changes to collective working agreements under certain conditions and setting up a registry for labour unions, which have called the move an attempt to control them.

Last week, ships remained docked in ports and public buses and trains ran on reduced services in Greece as public sector workers staged a walkout against the same planned changes. It was the first mass labour action since the government took office in July.

Private sector unions represent about 2.5 million workers. (Reporting by Renee Maltezou; Editing by Angus MacSwan)