Chinese Premier Wen Jiabao is demanding tougher anti-corruption efforts amid a huge political scandal over a now-suspended Politburo member whose wife has been named a suspect in the murder of a British businessman.

Wen's message, published Monday, differed little from previous calls to fight endemic corruption. But it comes amid a nationwide drive to support the Communist Party's decision to oust Bo Xilai from key positions and launch an investigation into what are described as serious breaches in discipline.

Media reports have raised questions about whether he tried to abuse his power to quash the investigation into his wife, Gu Kailai. Gu and a household employee are being investigated over the suspected murder of the Briton Neil Heywood.

There also have been strong suspicions that Bo, 62, grew fabulously wealthy through his ability to approve investments and make political appointments, although he has not been directly accused of any graft.

Wen wrote in an essay published in the party's main theoretical journal, Qiushi, that despite a series of measures enacted to curb corruption, greater determination and more effective anti-corruption tools are still needed.

Greater transparency and a reduction in the concentration of powers among some government departments is also needed to allow effective citizen supervision, Wen said.

"We need to deeply acknowledge that the greatest threat to the ruling party is corruption," Wen wrote.

Wen did not mention Bo by name or refer to the case directly. However, Wen has been the only top official to speak publicly about the matter, saying at his annual news conference last month that Chongqing officials need to understand its seriousness and put their house in order.

Also Monday, party newspaper Guangming Daily published the latest in a series of state media editorials calling on readers to support action against Bo and his wife and not to believe speculation that the politician's sidelining is linked to infighting among top leaders.

"Handling the serious breach of discipline is a measures embraced by the whole of the party and so-called 'inner-party conflict' has nothing to do with it," the editorial said.

Bo was once considered a leading candidate for the party's all-powerful Politburo Standing Committee when seven new members are expected to be picked at a party congress in the fall, in the first step in a generational handover of power to younger leaders.

However, his removal as Chongqing's Party Secretary on March 15 and suspension of his membership in the Politburo last week have effectively ended his political prospects and he could face trial.

A leaked transcript of a party official's briefing on the Bo matter, widely reported last month on Chinese online news sites, said that Bo's former police chief accused him of trying to halt an investigation into a family member, although the statement did not specify which member or for what crime. State media has since promised a thorough investigation into Bo, stressing that no one is above the law and no party member can interfere with police investigations.

Bo is the first Politburo member to be removed from office in five years and the scandal kicked up rumors of a political struggle involving Bo supporters intent on derailing succession plans calling Vice President Xi Jinping to lead the party for the next decade. Such allegations are fed by the same secrecy, political privilege and lack of outside supervision that are blamed for making high-level corruption such a major problem.

Efforts to require leading officials to declare their assets have found little traction while rules prohibiting officials and their family members from using political connections for personal gain are routinely flouted.

Bo was fired after Chongqing's former chief of police, Wang Lijun, made an extraordinary visit to the U.S. consulate in the southwestern city of Chongqing in early February. Wang is believed to have expressed his suspicions about the November death of Heywood to the Americans, who then tipped-off British diplomats who formally requested that China further investigate.

However, the British government on Monday said questions from Heywood's associates prompted it to ask the Chinese side to reopen their inquiries in February.

"We acted as soon as we thought the concerns about the case justified it," a spokeswoman for British Prime Minister David Cameron said, on condition of anonymity in line with policy.

Chinese authorities last week said Heywood previously had a close business relationship with Gu and the couple's son, Bo Guagua, who attended schools in Britain, but that the ties had recently soured.

Asked Monday about the Heywood case, Foreign Ministry spokesman Liu Weimin said that it was being handled under Chinese law but would take time to investigate fully.

Heywood's body was found Nov. 15 at the mountaintop Nanshan Holiday Hotel on the southern outskirts of Chongqing, according to people briefed on the investigation. Speculation has focused on the possibility that Heywood was poisoned, rather than dying from excess drinking or a heart attack as was originally claimed. Heywood's body was cremated without an autopsy being performed, and the hotel's remote location adds to the mystery surrounding his final hours.

A woman clerk reached by telephone said the hotel was privately owned but refused to name the owners. The woman, who refused to give her name because she wasn't authorized to speak to reporters, said she had no information about any guests dying at the 108-room facility.

Wang, the former police chief, was taken into custody and flown to Beijing after leaving the consulate on Feb. 6 and has not been heard from since. Bo and Gu are believed to be under some form of detention in Beijing but no details have been released on the state of the investigation or a possible trial.

Bo Guagua's whereabouts are not known, after British media reported over the weekend that he had been escorted from his apartment near Harvard University in Cambridge, Massachusetts.

The FBI declined comment, and U.S. Citizenship and Immigration Services referred queries to the State Department. Harvard police said its officers are not providing security for Bo, and the university did not comment.


Associated Press writer Rodrique Ngowi in Boston contributed to this report.