JD-S leader and Karnataka Chief Minister-designate H.D. Kumaraswamy on Monday met Congress President Rahul Gandhi and UPA Chairperson Sonia Gandhi to discuss ministerial berth sharing between the coalition partners ahead of his swearing-in ceremony on Wednesday.

The details of the meeting were not divulged but the sources said the Congress demanded two posts for Deputy Chief Ministers -- one for a Dalit and the other for a Lingayat, 12 for ministers and one for the Speaker. However, Kumaraswamy said the matter will be finalised when the two sides sit together on Tuesday in Bengaluru.

The Congress has authorised its General Secretary incharge of Karnataka K.C. Venugopal to discuss the matter with local Congress leadership, including former Chief Minister Siddaramaiah. He will also discuss the issue with the Janata Dal-Secular (JD-S) leadership.

"Rahulji cleared the modalities to be done. He has given permission to Venugopal to discuss all those matters and finalise everything. He will sit together to finalise things," Kumaraswamy told reporters after meeting the Gandhis.

He also invited both the Congress leaders to his oath-taking ceremony in Bengaluru on Wednesday. "Both agreed to come," he said.

Kumaraswamy earlier met Bahujan Samaj Party (BSP) chief Mayawati here and discussed plans of putting in place a Congress and JD-S coalition government. The JD-S contested the Karnataka election in a pre-poll alliance with the BSP and later had a post-poll tie-up with the Congress.

JD-S General Secretary and Spokesperson Danish Ali said Kumaraswamy and Congress leaders discussed "long term relationship on mutual trust" of the newly-formed coalition and vowed to give a joint contest to the BJP in Karnataka in 2019 Lok Sabha polls.

Ali told NDTV: "This is what we have decided. We will fight together."

Asked about Congress's demand of two Deputy Chief Ministers, he said: "Who will be their Deputy CM its up to them (Congress)."

Before Kumaraswamy meet the Gandhis, senior Congress leaders Ghulam Nabi Azad and Ashok Gehlot met Rahul Gandhi and are learnt to have discussed issues related to government formation in Karnataka.

Besides Sonia and Rahul Gandhi, Mayawati and Chief Ministers Arvind Kejriwal (Delhi), Pinarayi Vijayan (Kerala), Mamata Banerjee (West Bengal), Chandrababu Naidu (Andhra Pradesh) and K. Chandrashekar Rao (Telangana) are expected to attend the oath-taking ceremony.

Meanwhile, BJP President Amit Shah launched a scathing attack on both the parties and described the alliance as "unholy" while defending his party's decision to form the government.

"We were invited to form the government. There was nothing unethical," Shah told reporters here.

"The BJP emerged as the single-largest party in Karnataka. The mandate was in favour of the BJP. The Congress and the JD-S formed an alliance against the people's mandate. This is what I call an unholy alliance."

He said if the Congress and the JD-S had not "locked" their MLAs in five-star hotels and allowed them to interact with people, the JD-S would have supported the Bharatiya Janata Party (BJP) in government formation.

Shah said the BJP was invited to form the governments in Goa and Manipur earlier because the Congress did not stake claim despite emerging as the single-largest party as their leaders were "resting and sleeping".

The BJP chief said as the single-largest party, it was the BJP's right to stake claim. Responding to charges of attempts at horse trading by the BJP, Shah hit back, saying it was the Congress which sold its stable to form the state government.

Hitting out at the Congress for "preaching on democracy", Shah reminded how it formed the government in Goa in 1980 despite failing to win a single seat in the Assembly elections.