By Siva Sithraputhran KUALA LUMPUR (Reuters) - Malaysian opposition leader Anwar Ibrahim vowed on Tuesday to lead a "fierce movement" to reform the country's electoral system and challenge the results of an election he lost, starting with a rally of supporters this week. Anwar has contested the results of the most closely fought election since Malaysia was engulfed in race riots in 1969, accusing the ruling party of fraud, including use of immigrants as proxy voters, charges the government denies.

By Niluksi Koswanage and Stuart Grudgings KUALA LUMPUR (Reuters) - Malaysian Prime Minister Najib Razak may have to step down by the end of the year, ruling party sources said on Monday, after his coalition extended its 56-year rule but recorded its worst-ever election performance.

Anwar Ibrahim vowed Tuesday his Malaysian opposition would soon present evidence of government cheating in bitterly fought weekend elections as he called for a "fierce" campaign for electoral reform. Anwar insisted his three-party Pakatan Rakyat (People's Pact) alliance would not back down from its insistence that victory was stolen from it last Sunday, setting the stage for an extended battle with the government for public opinion.

Malaysia's Chinese minority has for decades gone about its business and left leadership to a Malay-dominated regime, but in weekend polls they deserted it in what the premier called a "Chinese tsunami". Prime Minister Najib Razak's term has since gone viral, touching off a debate over whether Sunday's bitter election battle presages a deepening divide between increasingly assertive urban Chinese and the country's majority Muslim Malays.