Yadav was on Wednesday posthumously conferred the Padma Vibhushan, the country's second highest civilian honour.
The government has made a mockery of Mulayam Singh Yadav's stature and contributions to the nation by conferring the Padma Vibhushan on him, Samajwadi Party leaders said on Thursday, demanding the country's highest civilian award Bharat Ratna for the party founder.
Yadav was on Wednesday posthumously conferred the Padma Vibhushan, the country's second highest civilian honour.
Party MLA Swami Prasad Maurya voiced his displeasure through a tweet.
"By giving Padma Vibhushan posthumously to Netaji Shri Mulayam Singh Yadav, the Government of India has made a mockery of Netaji's stature, work and contributions to the nation. If Netaji had to be respected then he should have been honoured with Bharat Ratna," Maurya tweeted in Hindi.
Mulayam Singh Yadav's daughter-in-law and the SP's Mainpuri MP Dimple Yadav said, "I feel that 'Netaji' (as Yadav was fondly referred to as) should have been honoured earlier. It will be our demand from the government to confer the Bharat Ratna on 'Netaji'," she said.
Party spokesperson I P Singh said the former defence minister should be honoured with the Bharat Ratna as soon as possible.
"Except for the Bharat Ratna, the highest civilian honour, no other honour befits the son of the soil late Mulayam Singh Yadav. An announcement should be made to give the Bharat Ratna to our respected Netaji without any delay," Singh tweeted.
Yadav, the Samajwadi Party founder and three-time Uttar Pradesh chief minister, died on October 10 last year.
SP leader Shivpal Singh Yadav told reporters in Etawah his brother Mulayam Singh Yadav got the award for his work.
He raised the voice for the poor, labourers, youth, students, lawyers, unemployed and worked for every section of society and took historic decisions in favour of army personnel when he was defence minister, Shivpal Singh Yadav said.
BJP state president Bhupendra Singh Chaudhary welcomed Mulayam Singh Yadav being honoured with the Padma Vibhushan.
"He had a big stature. He was active in social and political life for a long time in UP and also led the state. I welcome the decision of the government to confer him Padma Vibhushan," he said.
Deputy Chief Minister Keshav Prasad Maurya said conferring the Padma Vibhushan on Yadav is a welcome step by the government.
"It shows that the government works with the slogan of 'sabka saath, sabka vikas and sabke samman' without any political discrimination," he said.