Home Affairs and Law Minister K. Shanmugam yesterday described the conduct of the Singaporeans - including historian Thum Ping Tjin - who recently met Malaysian Prime Minister Mahathir Mohamad as "sad and regretful".

He was commenting on the group that met Tun Dr Mahathir in Putrajaya on Thursday, which included former student union leader Tan Wah Piow, Dr Thum, freelance journalist Kirsten Han, comic artist Sonny Liew, activist Jolovan Wham and Malaysian social activist Hishamuddin Rais. They invited Dr Mahathir to open a conference next year on the issue of opening up democratic space in South-east Asian countries.

Asked about the meeting at a community event at his ward of Chong Pang, Mr Shanmugam said: "We can have political differences within Singapore. It is the people's right.

"But I think we should never go out and invite someone foreign, a foreign politician, to intervene in our domestic politics. I think that's an absolute no-no."

After the meeting, Dr Thum wrote a Facebook post saying he had asked the Malaysian leader to "take leadership in South-east Asia for the promotion of democracy, human rights, freedom of expression and freedom of information".

Dr Thum said he also expressed hopes for closer relations between the people of Malaysia and Singapore, and presented Dr Mahathir with a copy of a book, Living With Myths In Singapore, co-edited by him.

Commenting on Dr Thum's post, Mr Shanmugam said: "I think it is quite clear what that means."

The minister's comments came a day after Marine Parade GRC MP Seah Kian Peng questioned Dr Thum in a Facebook post for suggesting that Singaporeans should also rejoice on Malaysia's independence day, among other things. Mr Seah added that "it appears quite clear to me that PJ Thum does not wish Singapore well".

Responding in a blog post that same night, Ms Han said Mr Seah appeared to have misunderstood the nature of the meeting with Dr Mahathir. On Dr Thum's post, she said: "PJ did not say that he asked Mahathir to bring democracy to Singapore, nor did I hear him say such a thing during the meeting."

She also said that Dr Thum's "happy unofficial independence day" wish to Singaporeans was not about declaring Singapore a part of Malaysia, but a reference to the Republic's history.

In the memoirs of Singapore's founding prime minister Lee Kuan Yew, The Singapore Story, Mr Lee had recounted how he had unilaterally declared Singapore independent from the British on Aug 31, 1963, in line with his push for Singapore to become part of the Federation of Malaysia. The federation was established two weeks later on Sept 16, 1963.

The merger proved acrimonious, over racial rights and representation as well as financial disputes, and culminated in the federal government expelling Singapore from Malaysia in August 1965. Since then, Singapore has marked Aug 9, 1965 as its independence day, while Malaysia regards Aug 31 as its Merdeka Day and Sept 16 as Malaysia Day.

Pointing to Ms Han's post, Mr Shanmugam said: "Kirsten Han then puts up a post saying that that is for South-east Asia and not Singapore. Where is Singapore if it is not in South-east Asia? Do we need a geography lesson?

"And we are not saying anything about Dr Mahathir but I think one needs to be careful with these things. And now to try and explain away what is so obvious doesn't do them much credit either."

The minister also noted that Dr Thum and Ms Han had tried to register a company, OSEA Pte Ltd, earlier this year.

"PJ and Kirsten are partners in a company they want to set up, which has taken foreign money, to also promote democracy, human rights and so on in Singapore, so this is not new. And I think it is all a bit sad," he said.

The Accounting and Corporate Regulatory Authority (Acra) had in April rejected the application to register OSEA Pte Ltd on the grounds that the registration would be contrary to Singapore's national interests.

Acra said that the purposes of the proposed company were clearly political in nature and had links to foreign funding from a group led by billionaire George Soros, which was set up to pursue a political agenda worldwide.

In a Facebook post yesterday afternoon, Ms Han said Mr Seah's allegations have triggered "a torrent of accusations of treason" against the group. "We are also getting death threats," she wrote.

She reiterated that his statements were "baseless" and called on him to retract them.

In a separate Facebook post, former political detainee Teo Soh Lung also urged Mr Seah to remove his post.

Mr Seah had flagged a comment that Ms Teo had posted about a video of a forum on Aug 18 on The Online Citizen's Facebook page, in which she wrote that "Singapore is part of Malaya la".

He said: "Really? This is what PJ Thum and Teo Soh Lung and the SDP (Singapore Democratic Party) believe in their heart of hearts?"

Yesterday, Ms Teo wrote a lengthy post in response and said the statement she had made was accurate in a historical context and timeframe.

She said she commented when Mr Hishamuddin was speaking about how the democratisation process in Malaysia began when the Federation of Malaya gained independence in 1957.

She also said Mr Seah had "deliberately misinform (sic)" the public that she is an SDP member. "I am not and he knows that."

Other participants in the meeting had earlier written about other aspects of their encounter with Dr Mahathir. Mr Wham said it was a fascinating experience overall, but added that some of Dr Mahathir's views - on Malays and lesbian, gay, bisexual and transgender rights - "are still very conservative and offensive".

Ms Han, in turn, noted in a blog post that she "came out of the meeting with few answers but a little more clarity".

"Although he's been talked up as a champion for democracy in Malaysia - don't we all love a clear-cut narrative - there are many ways in which Mahathir hasn't changed. He's still got his problematic views and stubborn positions, his own way of seeing things," she wrote.

Mr Liew noted that "it was clear from the outset that the group was made up of non-establishment folks, and there was always the possibility of the optics playing out in uncontrollable ways".