Indian Prime Minister Manmohan Singh will undergo heart bypass surgery over the weekend, officials say, after blockages were found in his arteries.

The 76-year-old leader will enter hospital in Delhi on Friday for the surgery on Saturday, a spokesman said.

Mr Singh previously had bypass surgery in the UK in 1990.

The new surgery will raise questions about Mr Singh's participation in the upcoming general elections, which must be held by May.

Foreign Minister Pranab Mukherjee is likely to take charge of prime ministerial meetings while Mr Singh recovers from the operation, reports say.

Mr Singh underwent tests earlier this week after he complained of chest pains.

He will undergo "coronary artery bypass graft surgery" performed by a team of doctors from the All India Institute of Medical Sciences, India's top state-run hospital, and the Asian Heart Institute in Mumbai, a government official said.

Gandhi dynasty

Doctors say there is "very little risk" associated with Mr Singh's surgery and that the prime minister should be fit to resume normal duties in "three to four weeks".

But his ill health may have an effect on the election campaign.

Though Congress party leaders have been saying that Mr Singh will be heading the party into the next elections, there have been reports that Rahul Gandhi, heir to India's powerful Gandhi family, is emerging as a successor.

It is not clear whether Mr Singh will be able to campaign intensively after his surgery, but the economist-politician has never been used by the party to woo voters in a big way.

"The Gandhi family and regional politicians continue to be more important," analyst Yashwant Deshmukh told Reuters news agency.

Apart from Mr Singh's heart bypass in 1990 he has also undergone wrist surgery, prostate gland surgery and a cataract removal procedure, officials said.

Mr Singh - the first prime minister from the Sikh community - has been heading the government since 2004.

He is widely regarded as the architect of the country's economic reform programme.

An academic-turned-civil servant who studied economics at Cambridge and Oxford, Mr Singh became India's finance minister in 1991 when the country was plunging into bankruptcy.

He is widely regarded as the cleanest politician in India, a subject dear to voters' hearts.