India's ruling party has told Pakistan that any further harassment of the country's top envoy in Islamabad could spark a crisis.

The warning from Arun Jaitley, the general secretary of the Bharatiya Janata Party, came on day two of a worsening diplomatic row.

The attack on the Indian diplomat in Pakistan has to be seen in conjunction with the recent threats to the people of Kashmir BJP leader Arun Jaitley

Both countries accuse each other of interfering in the work of their diplomatic staff.

"Pakistan's action is a deliberate attempt to violate diplomatic norms and precipitate a crisis," Mr Jaitley told reporters in Delhi.

He linked the row with recent threats by Kashmir militants, which he called "extremely disturbing".

Earlier, India's charge d'affaires in Islamabad said he was still being harassed by Pakistani agents - despite a complaint to the government.

Sudhir Vyas said he was now being subjected to ''aggressive surveillance''.

It's aggressive surveillance; I'm surrounded by three or four cars when I'm travelling Diplomat Sudhir Vyas

He earlier claimed that Pakistani vehicles had blocked his attempt to drive to a diplomatic function on Sunday.

That complaint sparked a sharp diplomatic exchange between India and Pakistan on Monday.

The nations both claimed their senior diplomats were being harassed by opposing intelligence agencies.

They urged each other to abide by international diplomatic norms.

Pakistan protest

Mr Vyas said that on Monday and Tuesday he had been subjected to ''aggressive trailing''.

''There has been no boxing in or halting of the flagged car and no blockade outside my residence as happened on the first day. But it's aggressive surveillance; I'm surrounded by three or four cars when I'm travelling,'' he said.

''They come in front, they come at the side, they come in the back and slow down or change speed and suddenly brake to try and throw us off balance.''

On Monday, the Pakistani Government rejected Mr Vyas' complaints.

The attack on India's parliament led to a full-scale stand off

Foreign Ministry spokesman Aziz Ahmed Khan said Pakistani diplomats in Delhi had been harassed by Indian security agencies for the past month or so and India had ignored Islamabad's protests.

Islamabad said it had lodged a complaint with India on 7 January over an unspecified harassment of Pakistani acting High Commissioner Jalil Abbas Jillani.

India said it was not aware of any incident of harassment.

The latest exchange came after Pakistan expressed anger at recent Indian missile tests and Indian Prime Minister Atal Behari Vajpayee's comments accusing Pakistan of being a centre of terrorism.

India recalled its ambassador to Islamabad in response to an attack on its parliament in December 2001 by Islamic militants.

It expelled Pakistan's ambassador last May as the nations came close to war.