Washington, July 23 : Vietnam's intensifying crackdown on free expression should be a top agenda item during President Truong Tan Sang's summit with President Barack Obama this week, Human Rights Watch said today.

Sang will be in the US from July 24 to 26 and Obama will host him at the White House Thursday.

Vietnam's previous president Nguyen Minh Triet visited Washington in June 2007, and Prime Minister Nguyen Tan Dung visited in June 2008.

Since those visits, a growing number of dissidents, bloggers, and religious leaders have been jailed in Vietnam, Human Rights Watch said.

Convictions in the first half of 2013 have overtook the total of those convicted in 2012, which in turn exceeds the number in 2011 and 2010.

"If criticizing the Vietnamese government is a crime, President Obama should show solidarity with dissidents by committing the crime himself," said John Sifton, Asia advocacy director at Human Rights Watch.

"President Sang cannot publicly justify his government's crackdown and should use this occasion to repudiate it."(IANS)