Train unions say they will push ahead with a planned strike next week after they failed to reach a deal with Sydney and New South Wales Trains management during late-night talks over pay and conditions.

In a notice to workers, the Rail Tram and Bus Union (RTBU) said train bosses came to the meeting with an offer, but it was deemed to be "not up to scratch".

The union said industrial action would go ahead as planned — with workers beginning an indefinite ban on overtime on Thursday, before a 24-hour work strike on Monday, January 29.

"There are still a range of conditions that we haven't got agreement on, including rostering concerns, job security, keeping the value of your Opal card when services are privatised and a fair and timely discipline process," the RTBU said in a written statement to members late on Monday night.

The head of the RTBU Alex Classens said the union wanted a fair deal.

"We still haven't got what got what we need to make our members happy," Mr Classens said.

"We just want a fair deal and we're not getting it yet.

"We've told them consistently that we want … guarantees about master roster conditions and we just need them to be serious and come to the table with a decent offer, and we haven't got it yet."

Sydney Trains boss Howard Collins said the unions had rejected three offers made during negotiations that stretched late into the night.

"The final offer [is] three-per-cent per annum with obviously some workplace changes. We've given them a lot of documentation. They've said they want to take it away."

Mr Collins said there would be more talks with union officials today.

"This is disappointing for us because the most important thing is for the customers to have some certainty about this industrial action being suspended.

"There is a lot of work to do but I think I'm still going to be here … whatever it takes.

"We're working pretty hard here to broker a deal. I'm hoping that some overnight thinking and some common sense may prevail."

'Avoid rush hour'

Mr Collins said a Saturday timetable would be implemented on Thursday in the face of the proposed industrial action.

"We've got a lot of information out there for customers that we'll be sharing with them. My advice to customers is to try and avoid those rush hour times. We will get you to your destination ... it may just mean changing your plans."

NSW Transport Minister Andrew Constance would not be drawn on whether the unions were asking for too much.

"I'm not going to commentate on what the position is of the unions," Mr Constance said.

"My very strong view is let's avert the strike and let's get a good package for the 9,500 employees of Sydney and New South Wales Trains."

The NSW Premier Gladys Berejiklian said it was not appropriate for her to intervene in the dispute.

"Given the imminence of next Monday, I'm really hoping there'll be a successful outcome later today," she said.

"I'm urging all parties to put aside other interests and really do what's in the interest of the travelling public."

Failed talks come after signs of improvement

On Friday, both the Government and the RTBU indicated the tone of talks had improved, after the week started with a war of words between the parties.

The union is seeking a 6 per cent annual pay increase for workers, much higher than the Government offer of a 2.5 per cent rise.

The union has also argued that recent timetable changes had stretched its workforce too far.

Before the weekend, Unions NSW secretary Mark Morey said both the unions and the Government hoped to eke out a more attractive package to take to workers this week.

The planned strike would begin at 12:01am on January 29, and could cause chaos for Sydney's commuters.