"It is a principle of the coalition dharma that a party does not poach members of its ally...The alliance partners should ensure that such a Laxman Rekha should never be crossed," he told reporters on the sidelines of his Janata durbar.
"BJP is committed to abide by principles of coalition dharma and will not cross the Laxman Rekha by poaching members of its alliance partner (JD-U)," he said.
Modi's comments were apparently aimed at downplaying those by the state unit BJP chief C P Thakur, who had recently claimed that several JD(U) leaders were in touch with his party and wanted to join it.
He said Thakur had made the remarks apparently with an intention to remind the two parties to abide by the principles of the coalition dharma.
On ex-BJP MLC Sanjay Jha joining JD(U) recently, Modi said it was an exceptional case. Jha had communicated his decision to BJP and its leaders, he said.