By Jyotsna Singh BBC correspondent in Delhi

The proposals are expected to pass the upper house reading

National and state MPs who leave the party they were elected to represent will lose their seats.

Such switches were previously considered legitimate if one-third or more of a party's MPs defected.

Analysts say defections generally took place for personal rewards, not for ideological reasons.

The new law effectively bars defections either individually or as a group.

Those defecting would be stripped of any office until they were re-elected as MPs.

The legislation will also limit the size of the council of ministers to 15% of the strength of the lower house of national and state parliaments.

The allegiance of MPs was often bought with the promise of a cabinet post.

Repeated misuse

The new laws, proposed by the BJP-led government, were passed by a majority vote in the lower house of the national parliament on Tuesday.

They must still go to the upper house, but are expected to pass as the Congress party has a majority there and supports the proposals.

The government says the changes are aimed at preventing the repeated misuse of the existing anti-defection law.

In one of the most recent examples, in January this year, a number of Congress party legislators in Uttar Pradesh switched en masse to the then-ruling Bahujan Samaj party.

Several government commissions and review committees over the years have recommended drastic changes to the anti-defection law, passed under a Congress government in 1985.

The committees said the existing law had actually promoted defections rather than curbed them.

The new laws have not been welcomed by everyone.

Some opposition MPs say they are not comprehensive enough.

But those opposed say stringent anti-defection laws threaten to discourage individual political dissent and so go against the very idea of democracy.