Downing Street has strenuously denied its refusal to invite the home secretary, Sajid Javid, to Donald Trump’s state banquet was Islamophobic.

Javid, who is standing to succeed Theresa May as Conservative leader, expressed frustration at the snub, describing it as “odd” after more junior ministers were invited.

He stopped short of claiming No 10 blocked his attendance because of his Muslim background, but the former Conservative party chair Sayeeda Warsi suggested it was an example of Islamophobia.

Warsi, who has urged the party to launch a full independent inquiry into allegations of anti-Muslim prejudice, tweeted: “To use my own phrase from 2011, ‘Islamophobia has passed the dinner table test’.”

Sayeeda Warsi (@SayeedaWarsi) To use my own phrase from 2011

“Islamophobia has passed the dinner table test” 🤷🏽‍♀️#StateBanquet #SajidJavid https://t.co/kh0oA7UcZE

The prime minister’s official spokesman said it was “categorically untrue” to link the snub to Javid’s Muslim background.

“The prime minister is proud to have appointed Sajid Javid as the country’s first Muslim home secretary,” he said.

Later, Warsi challenged her fellow Tory peer Howard Leigh, when he claimed the party had no prejudice against Javid. She tweeted that there had been numerous cases of party members and activists “targeting Sajid with anti-Muslim racism”.

Sayeeda Warsi (@SayeedaWarsi) Sadly Howard this isn’t true

Numerous cases of Islamophobia bought to the Partys attention incl members &activists targeting Sajid with anti Muslim racism - using demonising and derogatory language

As Jews &Muslims @Conservatives we must be united in fighting all forms of bigotry

In his first comments on the snub, Javid said he had written to the prime minister’s office asking why he was not invited, and suggested he was unconvinced by the answer he was given.

Asked by the BBC Radio 4 Today programme on Thursday why he thought he was not invited, Javid said: “I don’t know. I don’t know. I’ve asked but I haven’t got a … I was just told that normally home secretaries aren’t invited, so I don’t know.”

Asked how he felt about not being asked to attend when other more junior members of the cabinet including Michael Gove and Penny Mordaunt were invited, Javid said: “I don’t like it. For the reason that you have just said. It is odd.

“My office did ask No 10 and they said no. So you’d have to ask someone from No 10 why they made that decision.”

Asked whether the snub was linked to his Muslim background, Javid said: “No, I’m not saying that at all. I really don’t know. I haven’t got an … I’ve just been told that normally an invite doesn’t always go to a home secretary.”

Downing Street denied any malign intent, saying Javid was one of many ministers to have been disappointed.

“This was a state banquet hosted by Her Majesty the Queen, so I don’t think it’s appropriate to discuss in public who did or did not ask to attend,” the prime minister’s spokesman said. “But as with any state banquet, only a limited number of places are available to the government. A large number of ministers who expressed a wish to attend were not able to do so.”

A Downing Street source said there was a “fixed list” of people who must attend state banquets, including the prime minister, chancellor and foreign secretary, and there were in total eight slots available for Trump. The source pointed out May, when home secretary at the time of Barack Obama’s 2011 state visit, did not attend his banquet.

Javid’s predecessor as home secretary, Amber Rudd, was invited to at least one banquet for a head of state during her tenure. The Court Circular records she was a guest at the state banquet held in honour of the king of Spain in July 2017.

The former home secretary Jacqui Smith said she was invited to every state banquet during her two years in the post.

Jacqui Smith (@Jacqui_Smith1) V odd. I went to every state banquet for visiting leaders as Home Secretary https://t.co/odEMlbBWh4

Javid was one of several British politicians who criticised Trump in 2017 when the US president retweeted videos from the far-right group Britain First. Javid, who was then communities secretary, accused Trump of endorsing the views of “a vile, hate-filled racist organisation that hates me and people like me”. He added: “He is wrong and I refuse to let it go and say nothing.”

Earlier this month, the Muslim Council of Britain wrote to Theresa May asking her if Javid was not invited to the state banquet with Trump because he was of Muslim heritage.

The letter cited Trump’s Muslim travel ban, his retweeting of posts from Britain First and his criticism of the London mayor, Sadiq Khan. “We are all aware of the Islamophobia that President Trump has propagated and tolerated at the highest levels of his administration, both in rhetoric and policy,” the council said.

A council spokesman said it had yet to receive a reply to the letter. “If it is confirmed that the prime minister acceded to a request by President Trump to exclude Sajid Javid because he thought he was Muslim, this would constitute Islamophobia at the highest levels of our government,” he said.

“This would add to the wealth of evidence that already demonstrates the need for an inquiry into Islamophobia.”