Disability advocates are calling for ongoing funding for advocacy services amid concerns people will be left without access to vital support services.

Disability advocates and a raft of NSW politicians are demanding ongoing funding for advocacy services amid concerns people will be left without access to vital support services.

Hundreds of people attended the Stand By Me rally on Sunday morning, calling on the state government to commit to permanent funding for disability advocate organisations.

In 2017 the government confirmed funding for the services would end in June 2018 and be redirected to the National Disability Insurance Scheme.

However, in April 2018 premier Gladys Berejiklian and Minister for Disability Services Ray Williams announced up to $26 million for advocacy services until 2020 to provide access to these services during the transition to the NDIS.

Without funding beyond this time, the sector is concerned services will be forced to close leaving people without access to vital support.

More than 35,000 people have signed Stand By Me's online petition.

NSW Disability Advocacy Alliance chief Serena Ovens says people with a disability rely on advocacy services to make sure they are getting a fair deal.

"We need advocacy funding now and always, so post-2020 into the future. People with disability deserve the right to ensure that they have funding whenever they need help," Ms Ovens told AAP.

The NDIS clearly states it will not fund individual or systemic advocacy, Ms Ovens says.

Wendy de Meyrick, who attended the rally, has a 48-year-old son who is blind and has a brain injury among other disabilities.

"Without advocacy, I don't think that I'd be able to keep going - and advocacy from people who really understand what the issues are," Ms de Meyrick told AAP.

On Sunday, Minister for Disability Services Ray Williams confirmed services can expect to receive the same funding for 2019/2020 they received in 2018/19.

"The funding ensures people with disability in NSW are fully supported during implementation of the NDIS. It recognises it will take some time for the Commonwealth-led advocacy funding programs to reach maturity," Mr Williams said in a statement.

The coalition is "proactively meeting with advocacy organisations to ensure we address any gaps that arise in the lead up to 2020 and beyond".

Funding from the National Disability Advocacy Program, separate to the NDIS, can be applied to citizen, family, individual, legal, self and systemic advocacy.

The federal government is providing $60 million in funding to extend the NDAP and other advocacy programs to June 2020.

The National Disability Insurance Agency has also committed a grant round of $398 million over three years until 2022.