KUALA LUMPUR - Would-be arsonists in mostly Muslim Malaysia struck at a convent school and a sixth church on Sunday while church and government leaders called for calm in a row over Christians' use of the word Allah to refer to God.

The attacks threaten Prime Minister Najib Razak's plan to win back non-Muslim support before elections due by 2013 and may prevent investors from returning to Malaysia that has trailed Thailand and Indonesia for foreign investment.

The row, over a court ruling that allowed a Catholic newspaper to use Allah in its Malay-language editions, had prompted Muslims to protest at mosques and sparked arson attacks on a string of churches that saw a Pentecostalist church gutted.

The situation is under control and the people should not be worried, Home Minister Hishammuddin Hussein was quoted as saying by state news agency Bernama.

The attacks appear to have spread to other Malaysian states. Police said a petrol bomb was thrown at a guard house of a Catholic convent school in the sleepy town of Taiping, around 300 km (185 miles) from the capital Kuala Lumpur. It did not explode.

Several broken bottles and paint thinners were found at the Saint Louis church next to the convent and one of the country's oldest Anglican churches, All Saints, also in Taiping.

Police and church officials said attackers also hurled bricks and stones at glass windows of the Good Shepherd Catholic church in Miri -- a major logging and oil town in Sarawak state.

Sarawak and neighboring Sabah state are a key vote bank for Najib's National Front Party and home to a majority of Malaysia's Christians that account for 9.1 percent of the country's 28 million population. Many are non-English speaking adherents who have used the word Allah for decades.

On Sunday, Malaysians packed churches to listen to sermons of reaching out in friendship to all, including Muslims and keeping the peace in multi-religious Malaysia but many felt their religious rights were being trampled.

There are extremists in this country and the government seems unable to do anything, said Wilson Matayun, a salesman who attended Mass at St Anthony's Church in Kuala Lumpur. I am losing faith in our government. I pray it does not get worse.

Matayun is from Borneo island where the Catholic Herald says it has to use the word Allah to describe the Christian God in order to serve Christians who can only speak Malay.

The government has appealed against the ruling, a marked contrast to countries like Indonesia, Egypt and Syria where Christian minorities freely use the Arabic word to refer to God.

Some Malaysian Muslims say that the paper wants to use to word to confuse and convert Muslims and by midday Sunday 178,392 people has signed up for a Facebook group that opposes Christians using Allah.

Malaysia is mainly Muslim and Malay but there are sizable ethnic Chinese and Indian communities who mainly practice Christianity, Buddhism and Hinduism.

They handed the government its biggest losses in 2008 state and national elections in part due to feelings of religious marginalization and growing disillusionment with corruption.

Najib's handling of the issue will determine whether he can keep the support of the Malays and win back ethnic Chinese and Indian voters to solidify his grip on power after taking control of the government last year.

(Editing by Dominic Evans)

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