YANGON (REUTERS) - South-east Asian countries will discuss the crisis in Myanmar at a summit in Jakarta on Saturday (April 24), the Asean bloc's secretariat said on Tuesday, after the European Union imposed its toughest sanctions yet on the junta that seized power there on Feb 1.

Prime Minister Prayuth Chan-ocha said he would not be attending and that Thailand would be represented by Deputy Prime Minister Don Pramudwinai, who is also foreign minister.

"Some other countries will also send their foreign ministers," Prayuth, a former army chief who led a coup in Thailand in 2014, told reporters after a weekly cabinet meeting.

A Thai government official said on Saturday that Myanmar junta chief Min Aung Hlaing would go to Jakarta, although the Myanmar government has not commented. However, this is seen as unlikely - in previous stints of military rule, Myanmar has usually been represented at regional meetings by a prime minister or foreign minister.

The 10-member Association of South-east Asian Nations (Asean) has been trying to find a way to guide fellow member Myanmar out of the bloody turmoil that has followed the military coup against an elected government led by Nobel laureate Aung San Suu Kyi.

But there have been divergent views among Asean members over how to respond to the army's use of lethal force against civilians and the group's policies of consensus and non-interference in each others' affairs have limited its ability to act.

Indonesia, Malaysia, the Philippines and Singapore have sought to ramp up pressure on the junta. Thailand, Myanmar's neighbour, has said it is "gravely concerned" about escalating bloodshed, but close military ties and fears of a flood of refugees mean it is unlikely to go further.

Brunei, the current chair of the bloc, said after a meeting of the group's foreign ministers in March that Asean expressed concern about the situation in Myanmar and called on "all parties to refrain from instigating further violence".

Mr Romeo Jr Abad Arca, assistant director of the community relations division of the Asean Secretariat, said the summit would take place at its Jakarta headquarters on Saturday under strict health and security protocols due to the pandemic, confirming an earlier advisory.

Myanmar's military has shown little willingness to engage with its neighbours and no sign of wanting to talk to members of the government it ousted.

Pro-democracy politicians including ousted Members of Parliament from Suu Kyi's party announced the formation of a National Unity Government (NUG) on Friday.

It includes Suu Kyi, who has been in detention since the coup, as well as leaders of the pro-democracy protests and ethnic minorities.

The NUG says it is the legitimate authority and has called for international recognition and an invitation to the Asean meeting in Gen Min Aung Hlaing's place.

Former UN chief Ban Ki-moon urged his successor to engage directly with Myanmar's military to prevent an increase in post-coup violence and said South-east Asian countries should not dismiss the turmoil as an internal issue for Myanmar.

UN Secretary-General Antonio Guterres' special envoy on Myanmar, Ms Christine Schraner Burgener, has communicated with the military since the coup, but the junta has not allowed her to visit.

Malaysia's foreign minister on Tuesday said he hoped Myanmar would accept representatives from South-east Asian countries to observe and help the crisis-hit country return to normalcy.

"We hope that with the coming discussions in Jakarta, Myanmar will agree to accept representatives from the Asean chair Brunei or the Asean secretariat in Jakarta to observe and help Myanmar return to normalcy," Foreign Minister Hishammuddin Hussein told reporters, according to a video posted on his Twitter account.

Malaysian Prime Minister Muhyiddin Yassin will attend the meeting in Jakarta, Hishammuddin added.

In its firmest response yet to the ousting of the elected government led by Suu Kyi, the European Union said on Monday nine members of the junta's State Administration Council, formed the day after the coup, had been targeted with travel bans and asset freezes. Information Minister U Chit Naing was sanctioned also.

The decision follows similar measures by the United States.

Gen Min Aung Hlaing and Mr Myint Swe, who has been acting president since the coup, were blacklisted by the EU last month.

"The military forces and authorities operating under the control of the SAC have committed serious human rights violations since February 1, 2021, killing civilian and unarmed protesters," the EU said.

Myanmar's state media said on Monday that 258 civilians have died in violence in the country in anti-military protests since Feb 1 and that other tolls were exaggerated.

According to the Assistance Association for Political Prisoners (AAPP) activist group, 738 people have been killed by security forces since the coup.