Two Hong Kong lawmakers who advocate a split from China should be banned from taking up their seats, government lawyers argued in court Thursday, as concerns grow Beijing will wade into the escalating row.

Widespread fears that China is tightening its grip on the semi-autonomous city are fuelling an independence movement in Hong Kong.

At a judicial review seeking to disqualify Yau Wai-ching and Baggio Leung from the legislature at Hong Kong's High Court Thursday, the government's counsel insisted authorities had not asked Beijing to step in.

"The issues... should be solved in the judicial system," said lawyer Benjamin Yu.

The city's leader Leung Chun-ying, who brought the case against the pair, said earlier this week he could not rule out the possibility that Beijing might get involved.

Local media reports say China's top legislative body, the National People's Congress Standing Committee (NPCSC), could issue an "interpretation" of Hong Kong's constitution on Monday relating to the case.

But Yu said the Hong Kong government had not received any confirmation of that happening.

He argued Baggio and Yau should not be allowed to take up their seats in the Legislative Council (Legco) -- the city's lawmaking body -- because they failed to swear allegiance to Hong Kong as an "inalienable part of China" at an oath-taking ceremony three weeks ago.

Instead, they draped themselves in "Hong Kong is not China" flags and altered the wording of their oaths, including derogatory terms and expletives.

"Our case is that Leung and Yau have been duly requested to take the Legco oath on October 12 this year and they have declined," Yu told the court.

"If you do not believe Hong Kong is an inalienable part of China then you have no business in Legco," he added.

- 'Severe blow' -

Yau and Baggio won seats in citywide polls last month, in which a number of new lawmakers advocating self-determination or independence swept to victory.

Legco president Andrew Leung initially agreed to give them a second chance at taking their oath.

But that decision is being challenged in court by city leader Leung and the justice secretary Rimsky Yuen, a move which critics say shows the executive branch riding roughshod over the legislature.

The Legco president, a pro-Beijing lawmaker, is a defendant in the case, alongside Baggio and Yau.

His lawyer argued Thursday that he had been "unnecessarily and wrongly" brought into the proceedings.

Lawyers for Yau and Baggio said the Legco should be able to make an independent decision about their oath.

"(It is) not a matter for the court, it is a matter entirely within the walls of Legco," said Hectar Pun, representing Baggio.

The hearing finished Thursday afternoon and judge Thomas Au said he would hand down his judgement as soon as possible.

Hong Kong's Bar Association has warned against any interference in the court process by Beijing, saying it would "deal a severe blow to the independence of the judiciary".

But China's state-run newspaper Global Times on Thursday cited legal experts expressing support for the move.

An interpretation by Beijing would "end the constitutional crisis and paralysis within the Legco, giving clear and stable guidance on (the implementation of) the Basic Law (Hong Kong's constitution)," it quoted Tian Feilong, a legal expert at Beihang University, as saying.

The Legco descended into chaos for the third consecutive week Wednesday after Yau and Baggio tried to force their way into the chamber to take their oaths, having been temporarily barred pending the judicial review.

Six security staff were injured during the clashes.